Category Archives: C Programs

C Programs

C Program to Compare two Strings

C Program to Compare Two Strings

In this tutorial, we will learn to create a C program that will Compare Two Strings in C programming.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic of C programming.
For loop and its concepts in C Programming.
Conditional Statements in C Programming.

Algorithm:-

1. Declaring the variables for the program.

2. Taking the input string one from the user.

3. Taking the input string two from the user.

4. Comparing the string one and two.

5. Printing the result .

6. End the program.

1. Declaring the variables for the program.

2. Taking the input string one from the user.

3. Taking the input string two from the user.

4. Comparing the string one and two.

5. Printing the result .

6. End the program.

What is a string?

As we all know, the string is a collection of characters, symbols, digits, and blank spaces. In strings, only one variable is declared which can store multiple values.

Compare Two Strings

First will take the elements of string 1 from the user. Then will take the elements of string 2 from the user. Then will compare the two taken strings without using the predefined functions. i.e. compare them without using the strcmp function.

With the help of this program, we can Compare Two Strings.

Program code:-

/* C program to Compare Two Strings */
#include <stdio.h>
#include <string.h>
int main()
{
    //DECLARING THE VARIABLES.
   char String1[100], String2[100];
   int  i;
    //TAKING INPUT STRING ONE FROM THE USER
   printf("\n Please Enter the First String :  ");
   gets(String1);
   //TAKING INPUT STRING TWO FROM THE USER
   printf("\n Please Enter the Second String :  ");
   gets(String2);
   //COMPARING STRINGS WITHOUT USING THE STRCMP()
   for(i = 0; String1[i] == String2[i] && String1[i] == '\0'; i++);
   if(String1[i] < String2[i])
   {
       //PRINTING IF STING ONE IS LESS THAN STRING TWO
   printf("\n string 1 is Less than string 2");
}
else if(String1[i] > String2[i])
   {
       //PRINTING IF STING TWO IS LESS THAN STRING ONE
   printf("\n string 2 is Less than string 1");
}
else
   {
       //PRINTING IF STING ONE IS EQUAL TO STRING TWO
   printf("\n string 1 is Equal to string 2");
}
   return 0;
}

/* C program to Compare Two Strings */

#include <stdio.h>

#include <string.h>

int main()

{

//DECLARING THE VARIABLES.

char String1[100], String2[100];

int i;

//TAKING INPUT STRING ONE FROM THE USER

printf("\n Please Enter the First String : ");

gets(String1);

//TAKING INPUT STRING TWO FROM THE USER

printf("\n Please Enter the Second String : ");

gets(String2);

//COMPARING STRINGS WITHOUT USING THE STRCMP()

for(i = 0; String1[i] == String2[i] && String1[i] == '\0'; i++);

if(String1[i] < String2[i])

{

//PRINTING IF STING ONE IS LESS THAN STRING TWO

printf("\n string 1 is Less than string 2");

}

else if(String1[i] > String2[i])

{

//PRINTING IF STING TWO IS LESS THAN STRING ONE

printf("\n string 2 is Less than string 1");

}

else

{

//PRINTING IF STING ONE IS EQUAL TO STRING TWO

printf("\n string 1 is Equal to string 2");

}

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

string1[100] = it will hold the string value.
string2[100] = it will hold the string value.
i = it will hod the integer value that will control the for loop

Taking Input string 1 from the user.

Taking Input string 2 from the user.

Printing Output compared string.

C Program to Concatenate Two Strings

In this tutorial, we will learn to create a C program that will Concatenate Two Strings in C programming.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Using Strings in C Programming.

What is a string?

As we all know, the string is a collection of characters, symbols, digits, and blank spaces. In strings, only one variable is declared which can store multiple values.

What is Concatenation?

Concatenation means to join two different words i.e. multiple Strings into a single string value.

Algorithm:-

1. Declaring the variables for the program.

2. Taking input string 1 and 2 from the user.

3. Concatinating the string from the taken variable.

4. Printing the result string.

5. End the program.

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						1. Declaring the variables for the program.
 
2. Taking input string 1 and 2 from the user.
 
3. Concatinating the string from the taken variable.
 
4. Printing the result string.
 
5. End the program.

Program to Concatenate Two Strings:-

First will take the input string one from the user. Then we will take a second-string from the user and now we will concatenate that two stings. And at last, will print the resultant string.

Using the below program example.

Program Code:-

/* C Program to Concatenate Two Strings */
#include <stdio.h>  
int main()  
{
  //Declaring the required variables for the program.
  char string1[20]; // declaration char array1   
  char string2[20]; // declaration char array2   
  int i=0,j=0; // integer variables declaration 
  char *str1; // of char pointer declaration
  char *str2;  // char pointer  declaration
  str1=string1;  
  str2=string2;  
  //Taking Input From the user
  printf("Enter the first string\n");  
  scanf("%s",string1);  
  printf("\nEnter the second string\n");  
  scanf("%s", string2);  
  while(string1[i]!='\0')  
  {  
     ++str1;  
     i++;  
  }  
  while(string2[j]!='\0')  
  {  
      *str1=*str2;  
      str1++;  
      str2++;  
      j++;  
  }  
  printf("The concatenated string is %s",string1);  
return 0;  
}

/* C Program to Concatenate Two Strings */

#include <stdio.h>

int main()

{

//Declaring the required variables for the program.

char string1[20]; // declaration char array1

char string2[20]; // declaration char array2

int i=0,j=0; // integer variables declaration

char *str1; // of char pointer declaration

char *str2; // char pointer declaration

str1=string1;

str2=string2;

//Taking Input From the user

printf("Enter the first string\n");

scanf("%s",string1);

printf("\nEnter the second string\n");

scanf("%s", string2);

while(string1[i]!='\0')

{

++str1;

i++;

}

while(string2[j]!='\0')

{

*str1=*str2;

str1++;

str2++;

j++;

}

printf("The concatenated string is %s",string1);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

string1[20] = it will hold the string value.
string2[20] = it will hold the string value.
i = it will hold the integer value.
j = it will hold the integer value.
*str1 = pointer type variable 1.
*str2 = pointer type variable 2.

Input strings from the user.

While loop body for concatenating the strings using the pointers and printing the concatenated string.

C Program to Copy String

In this tutorial, we will learn to create a C program that will Copy String in C programming.

Prerequisites

Before starting with this tutorial, we assume that you are the best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Using Strings in C Programming.

What is a string?

As we all know, the string is a collection of characters, symbols, digits, and blank spaces. In strings, only one variable is declared which can store multiple values.

Algorithm:-

1. Declaring the variables for the program.

2. Add a string to the variable

3. Copy from the taken variable.

4. Printing the result string.

5. End

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						1. Declaring the variables for the program.
 
2. Add a string to the variable
 
3. Copy from the taken variable.
 
4. Printing the result string.
 
5. End

Program to Copy String

First, will take the input string from the user. And then will copy the string. The C programming language has many pre-defined functions for string manipulation. In today’s tutorial, we will do copy work with the help of a strcpy() function. It is used for copying the string from one variable to another variable.

With the help of the below program, we can Copy String.

Program Code:-

#include <stdio.h>
#include <string.h>
int main()
{
  /* Declaring the variable for the program required to complete the operation  */
  char var1[1000], var2[1000];
  
  /* Taking the input string from the user for the program */
  printf("Input a string\n");
  gets(var1);
  
  /* Copying the string with the help of a predefined function 
  strcpy  */
  strcpy(var2, var1);
  
  /* Printing the string to the user in output */
  printf("var1 string: %s\n", var1);
  printf("var2 string: %s\n", var2);

  return 0;
}

#include <stdio.h>

#include <string.h>

int main()

{

/* Declaring the variable for the program required to complete the operation */

char var1[1000], var2[1000];

/* Taking the input string from the user for the program */

printf("Input a string\n");

gets(var1);

/* Copying the string with the help of a predefined function

strcpy */

strcpy(var2, var1);

/* Printing the string to the user in output */

printf("var1 string: %s\n", var1);

printf("var2 string: %s\n", var2);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

var1 = it will hold the string value.
var2 = it will hold the string value.

Taking input string from the user for copying the string.

Copying the string with the help of the assignment operator.

Printing the output copied string1 and string2.

C Program to Print Smiling face

In this tutorial, we will learn to create a C program that will Print Smiling face in C programming.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
For loop in C programming.

Program to Print Smiling face

As we all know the String is a collection of character data types. In strings, only one variable is declared which can store multiple values. First, we will take the input number from the user for a number of smiles. Then we will Print the Smiling face using the for loop. The ASCII value of 1 is smile.

With the help of this program, we can Print a Smiling face

Algorithm:-

1. Declare the variables for the program. 

2. Take the input string from the user. 

3. <strong>Swap Two Strings</strong>. 

4. Print the output. 

5. End the program.

1. Declare the variables for the program.

2. Take the input string from the user.

3. Swap Two Strings.

4. Print the output.

5. End the program.

Program to Print Smiling face:-

/* C Program to Print Smiling face */

#include<stdio.h>
void main()
{
    //Declaing the variable for the program
    int smile=1, i, limit;
    //smile= It will hold the integer value 1 which is smile in ASCII
    //i = It will hold the integer value for controlling the for loop
    //limit = It will hold the integer value for the number of smily
    
    //Taking the input from the user for quantity of smile.
    printf("How many smiley face you want to print ? ");
    scanf("%d",&limit);
    
    //Printing the smile with the help of for loop
    for(i=0; i<limit; i++)
        {
            printf("%c ",sml);
        }
        
    return 0;
}

/* C Program to Print Smiling face */

#include<stdio.h>

void main()

{

//Declaing the variable for the program

int smile=1, i, limit;

//smile= It will hold the integer value 1 which is smile in ASCII

//i = It will hold the integer value for controlling the for loop

//limit = It will hold the integer value for the number of smily

//Taking the input from the user for quantity of smile.

printf("How many smiley face you want to print ? ");

scanf("%d",&limit);

//Printing the smile with the help of for loop

for(i=0; i<limit; i++)

{

printf("%c ",sml);

}

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

smile= It will hold the integer value 1 which is a smile in ASCII.
i = It will hold the integer value for controlling the for loop.
limit = It will hold the integer value for the number of smiles.

Taking the input number of smiles.

Printing the output smile.

C Program to Swap Two Strings

In this tutorial, we will learn to create a C program that will Swap Two Strings in C programming.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Conditional statements in C programming.
String functions of c programming.

Program to Swap Two Strings

As we all know the String is a collection of character data types. In strings, only one variable is declared which can store multiple values. First, we will take the input string from the user. Then we will Swap Two Strings using the third variable that will help to swap.

With the help of this program, we can Swap Two Strings.

Algorithm:-

1. Declare the variables for the program. 

2. Take the input string from the user. 

3. <strong>Swap Two Strings</strong>. 

4. Print the output. 

5. End the program.

1. Declare the variables for the program.

2. Take the input string from the user.

3. Swap Two Strings.

4. Print the output.

5. End the program.

Program to Swap Two Strings:-

#include <stdio.h>
/* Including the header file for the suuport the string functions */
#include <string.h>
int main()
{
  /* declaring the variables for the program */
  char first[100], second[100], flag[100];
  /* Taking input from the user string 1 */
  printf("Enter first string\n");
  gets(first);
  /* Taking input from the user string 2 */
  printf("Enter second string\n");
  gets(second);
  /* Printing string before swapping */
  printf("\nBefore Swapping\n");
  printf("First string: %s\n", first);
  printf("Second string: %s\n\n", second);
  /* Swapping the strings */
  strcpy(flag, first);
  strcpy(first, second);
  strcpy(second, flag);
  /* Printing string after swapping */
  printf("After Swapping\n");
  printf("First string: %s\n", first);
  printf("Second string: %s\n", second);

  return 0;
}

#include <stdio.h>

/* Including the header file for the suuport the string functions */

#include <string.h>

int main()

{

/* declaring the variables for the program */

char first[100], second[100], flag[100];

/* Taking input from the user string 1 */

printf("Enter first string\n");

gets(first);

/* Taking input from the user string 2 */

printf("Enter second string\n");

gets(second);

/* Printing string before swapping */

printf("\nBefore Swapping\n");

printf("First string: %s\n", first);

printf("Second string: %s\n\n", second);

/* Swapping the strings */

strcpy(flag, first);

strcpy(first, second);

strcpy(second, flag);

/* Printing string after swapping */

printf("After Swapping\n");

printf("First string: %s\n", first);

printf("Second string: %s\n", second);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

first[100] = it will hold the string value.
second[100] = it will hold the string value.
flag[100] = it will hold the integer value.

Taking the input string 1 from the user.

Taking the input string 2 from the user.

Print string before the swap.

Swapping the strings,

Printing the output.

C Program to Write Content to File

In this tutorial, you will learn about the C Program to Write Content to File with a practical example.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Conditional Statements in C programming.
Using file functions of c language.

Program to Write Content to File.

As we all know the file is a collection of characters, integers, and many data types. In strings, only one variable is declared which can store multiple values. First will take the file from the user. Then will Check that file if it’s empty or not. The C programming language has many pre-defined functions for file manipulation. but in today’s tutorial, Write Content to File from the user.

With the help of the below program, we can Write Content to File.

Algorithm:-

1. Declaring the variables for the program. 

2. Opening the file in write mode. 

3. Taking the string input from the user

4. Adding the string to the file. 

5. Printing the results. 

6. End program.

1. Declaring the variables for the program.

2. Opening the file in write mode.

3. Taking the string input from the user

4. Adding the string to the file.

5. Printing the results.

6. End program.

Program to Write Content to File:-

/* C Program to Write Content to File */

#include <stdio.h>
#include <stdlib.h>

int main() 
{
    //declairing the variable for the program
    char sentence[1000];
    // creating file pointer to work with files
    FILE *fptr;

    // opening file in writing mode
    fptr = fopen("program.txt", "w");

    // exiting program 
    if (fptr == NULL) {
        printf("Error!");
        exit(1);
    }
    //Taking the string from user to be inserted in the file
    printf("Enter a sentence:\n");
    //Adding that string to the file and closing the file
    fgets(sentence, sizeof(sentence), stdin);
    fprintf(fptr, "%s", sentence);
    fclose(fptr);
    
    return 0;
}

/* C Program to Write Content to File */

#include <stdio.h>

#include <stdlib.h>

int main()

{

//declairing the variable for the program

char sentence[1000];

// creating file pointer to work with files

FILE *fptr;

// opening file in writing mode

fptr = fopen("program.txt", "w");

// exiting program

if (fptr == NULL) {

printf("Error!");

exit(1);

}

//Taking the string from user to be inserted in the file

printf("Enter a sentence:\n");

//Adding that string to the file and closing the file

fgets(sentence, sizeof(sentence), stdin);

fprintf(fptr, "%s", sentence);

fclose(fptr);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

*fptr = it will hold the address value.
sentence[1000] = it will hold the string data.

opening the file in write mod.

If the pointer is null then exit.

Taking the input sting from the user.

Closing the file.

C Program to Read a File

C Program to Read File

In this tutorial, you will learn about the C Program to Read File with a practical example.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Concepts of while loop.
Conditional Statements in C programming.
Using file functions of c language.

Program to reading a file.

With the help of the below program, we can Read a File.

Algorithm:-

1. Declaring the variables for the program. 

2. Taking the input from the user. 

3. <strong>Reading</strong> the file. 

4. <strong>Displaying</strong> the file if there is any data in it. 

5. Printing the results. 

6. End program.

1. Declaring the variables for the program.

2. Taking the input from the user.

3. Reading the file.

4. Displaying the file if there is any data in it.

5. Printing the results.

6. End program.

Program:-

/* C Program to Read File */
#include<stdio.h>
int main()
{
    //declaring the vaiables for the program
    char fname[20], str[500];
    FILE *fp;
    //Taking the input file name to read and print on screen
    printf("Enter the Name of File: ");
    //getting the file name by the user.
    gets(fname);
    fp = fopen(fname, "r");
    //if the file is null then the program execution will end .
    if(fp==NULL)
        printf("Error Occurred while Opening the File!");
    else
    //redaing and printing the data form the file on the screen.
    {
        fscanf(fp, "%[^\0]", str);
        printf("\nContent of File is:\n\n");
        printf("%s", str);
    }
    //Closing the file open by the program to read
	fclose(fp);

    return 0;
}

/* C Program to Read File */

#include<stdio.h>

int main()

{

//declaring the vaiables for the program

char fname[20], str[500];

FILE *fp;

//Taking the input file name to read and print on screen

printf("Enter the Name of File: ");

//getting the file name by the user.

gets(fname);

fp = fopen(fname, "r");

//if the file is null then the program execution will end .

if(fp==NULL)

printf("Error Occurred while Opening the File!");

else

//redaing and printing the data form the file on the screen.

{

fscanf(fp, "%[^\0]", str);

printf("\nContent of File is:\n\n");

printf("%s", str);

}

//Closing the file open by the program to read

fclose(fp);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

*fp = it will hold the address value.
str[500] = it will hold the string data.
fname[20] = it will hold the string data.

Taking input file name.

Opening the file and reading it.

Displaying the data from the file.

C Program to Read & Display File

In this tutorial, you will learn about the C Program to Read & Display File with a practical example.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Concepts of while loop.
Conditional Statements in C programming.
Using file functions of c language.

Program to reading & Display File

With the help of the below program, we can Read & Display.

Algorithm:-

1. Declaring the variables for the program. 

2. Taking the input from the user. 

3. Reading the file. 

4. <strong>Displaying</strong> the file if there is any data in it. 

5. Printing the results. 

6. End program.

1. Declaring the variables for the program.

2. Taking the input from the user.

3. Reading the file.

4. Displaying the file if there is any data in it.

5. Printing the results.

6. End program.

Program:-

/* C Program to Read & Display File */
#include<stdio.h>
int main()
{
    //declaring the vaiables for the program
    char fname[20], str[500];
    FILE *fp;
    //Taking the input file name to read and print on screen using c program
    printf("Enter the Name of File: ");
    //getting the file name by the user.
    gets(fname);
    fp = fopen(fname, "r");
    //if the file is null then the program execution will end .
    if(fp==NULL)
        printf("Error Occurred while Opening the File!");
    else
    //redaing and printing the data form the file on the screen.
    {
        fscanf(fp, "%[^\0]", str);
        printf("\nContent of File is:\n\n");
        printf("%s", str);
    }
    //Closing the file open by the program to read
	fclose(fp);

    return 0;
}

/* C Program to Read & Display File */

#include<stdio.h>

int main()

{

//declaring the vaiables for the program

char fname[20], str[500];

FILE *fp;

//Taking the input file name to read and print on screen using c program

printf("Enter the Name of File: ");

//getting the file name by the user.

gets(fname);

fp = fopen(fname, "r");

//if the file is null then the program execution will end .

if(fp==NULL)

printf("Error Occurred while Opening the File!");

else

//redaing and printing the data form the file on the screen.

{

fscanf(fp, "%[^\0]", str);

printf("\nContent of File is:\n\n");

printf("%s", str);

}

//Closing the file open by the program to read

fclose(fp);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

*fp = it will hold the address value.
str[500] = it will hold the string data.

Taking input file name.

Opening the file and reading it.

Displaying the data from the file.

Closing the file.

C Program to Copy a File

In this tutorial, you will learn about the C Program to Copy a File with a practical example.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Concepts of while loop.
Conditional Statements in C programming.
Using file functions of c language.

Program to Copy a File

With the help of this program, we can Copy a File

Algorithm:-

1. Declaring the variables for the program. 

2. Taking the input from the user. 

3. Reading the file. 

4. <strong>Copy a File </strong>if there is any data in it. 

5. Printing the results ouput message. 

6. End program.

1. Declaring the variables for the program.

2. Taking the input from the user.

3. Reading the file.

4. Copy a File if there is any data in it.

5. Printing the results ouput message.

6. End program.

Program:-

#include <stdio.h>
#include <stdlib.h>
int main()
{
    //declaring the variables for the program 
   char ch, source_file[20], target_file[20];
   FILE *source, *target;
   //taking input file from the user to copy
   printf("Enter name of file to copy\n");
   gets(source_file);

   source = fopen(source_file, "r");

   if (source == NULL)
   {
      printf("Press any key to exit...\n");
      exit(EXIT_FAILURE);
   }
   //Printing the output for the program
   printf("Enter name of target file\n");
   gets(target_file);

   target = fopen(target_file, "w");

   if (target == NULL)
   {
      fclose(source);
      printf("Press any key to exit...\n");
      exit(EXIT_FAILURE);
   }

   while ((ch = fgetc(source)) != EOF)
      fputc(ch, target);
   //output message for successful copy of the file
   printf("File copied successfully.\n");

   fclose(source);
   fclose(target);

   return 0;
}

#include <stdio.h>

#include <stdlib.h>

int main()

{

//declaring the variables for the program

char ch, source_file[20], target_file[20];

FILE *source, *target;

//taking input file from the user to copy

printf("Enter name of file to copy\n");

gets(source_file);

source = fopen(source_file, "r");

if (source == NULL)

{

printf("Press any key to exit...\n");

exit(EXIT_FAILURE);

}

//Printing the output for the program

printf("Enter name of target file\n");

gets(target_file);

target = fopen(target_file, "w");

if (target == NULL)

{

fclose(source);

printf("Press any key to exit...\n");

exit(EXIT_FAILURE);

}

while ((ch = fgetc(source)) != EOF)

fputc(ch, target);

//output message for successful copy of the file

printf("File copied successfully.\n");

fclose(source);

fclose(target);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

*source = it will hold the address value.
*target = it will hold the new file data.

Taking input file name.

Reading the file and taking the target file.

Copying the file.

Printing the output.

C Program to List Files in Directory

In this tutorial, you will learn about the C Program to List Files in Directory with a practical example.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Concepts of while loop.
Conditional Statements in C programming.
Using file functions of c language.

Program to List Files in Directory

As we all know the file is a collection of characters, integers, and many data types. In strings, only one variable is declared which can store multiple values. First will take the file from the user. Then will Check that directory if it’s empty or not. The C programming language has many pre-defined functions for file manipulation. but in today’s tutorial, we will List Files in Directory.

With the help of this program, we can List Files in the Directory

Algorithm:-

1. Declaring the variables for the program. 

2. Taking the input from the user. 

3. Reading the directory. 

4. <strong>Viewing the directory </strong>if there are any files. 

5. Printing the results data. 

6. End program.

1. Declaring the variables for the program.

2. Taking the input from the user.

3. Reading the directory.

4. Viewing the directory if there are any files.

5. Printing the results data.

6. End program.

Program:-

#include <stdio.h>
#include <dirent.h>

int main()
{
    //declaring the variables for the program
	struct dirent *de; // Pointer for directory entry

	// opendir() returns a pointer of DIR type.
	DIR *dr = opendir(".");

	if (dr == NULL) // opendir returns NULL if couldn't open directory
	{
		printf("Could not open current directory" );
		return 0;
	}

	// Refer http://pubs.opengroup.org/onlinepubs/7990989775/xsh/readdir.html
	// for readdir()
	while ((de = readdir(dr)) != NULL)
			printf("%s\n", de->d_name);

	closedir(dr);	
	return 0;
}

#include <stdio.h>

#include <dirent.h>

int main()

{

//declaring the variables for the program

struct dirent *de; // Pointer for directory entry

// opendir() returns a pointer of DIR type.

DIR *dr = opendir(".");

if (dr == NULL) // opendir returns NULL if couldn't open directory

{

printf("Could not open current directory" );

return 0;

}

// Refer http://pubs.opengroup.org/onlinepubs/7990989775/xsh/readdir.html

// for readdir()

while ((de = readdir(dr)) != NULL)

printf("%s\n", de->d_name);

closedir(dr);

return 0;

}

Output:-

In the above program, we have first initialized the required variable.

*de = it will hold the address value.
*dr = it will hold the dir data.

Opening and reading the directory.

Reading the directory if empty then.

Generating the list and printing the list of files present in the directory using the while loop.

C Program to Encrypt & Decrypt a File

In this tutorial, you will learn about the C Program to Encrypt & Decrypt a File with a practical example.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.
Concepts of while loop.
Conditional Statements in C programming.
Using file functions of c language.

Program to Encrypt & Decrypt a File

As we all know the file is a collection of characters, integers, and many data types. In strings, only one variable is declared which can store multiple values. First will take the file from the user. Then will encrypt that file so that anyone can not read it directly. The C programming language has many pre-defined functions for file manipulation. but in today’s tutorial, we will Encrypt & Decrypt a File.

With the help of this program, we can Encrypt & Decrypt a File

Algorithm:-

1. Declaring the variables for the program. 

2. Taking the input file from the user. 

3. Reading the file. 

4. <strong>Encrypt & Decrypt a File</strong>. 

5. Printing the results data. 

6. End program.

1. Declaring the variables for the program.

2. Taking the input file from the user.

3. Reading the file.

4. Encrypt & Decrypt a File.

5. Printing the results data.

6. End program.

Program:-

#include <stdio.h>
#include <stdlib.h>

void main()
{
    //declaring the variable for the program
	char fname[20], ch;
	FILE *fn, *fne;
	
	printf("\n\n Encrypt a text file :\n");
	printf("--------------------------\n"); 	
	//taking input from the user
	printf(" Input the name of file to encrypt : ");
	scanf("%s",fname);	
    
	fn=fopen(fname, "r");
	if(fn==NULL)
	{
		printf(" File does not exists or error in opening..!!");
		exit(1);
	}
	fne=fopen("temp.txt", "w");
	if(fne==NULL)
	{
		printf(" Error in creation of file temp.txt ..!!");
		fclose(fn);
		exit(2);
	}
	while(1)
	{
		ch=fgetc(fn);
		if(ch==EOF)
		{
			break;
		}
		else
		{
			ch=ch+100;
			fputc(ch, fne);
		}
	}
	fclose(fn);
	fclose(fne);
	fn=fopen(fname, "w");
	if(fn==NULL)
	{
	    //printing the output
		printf(" File does not exists or error in opening..!!");
		exit(3);
	}
	fne=fopen("temp.txt", "r");
	if(fne==NULL)
	{
		printf(" File does not exists or error in opening..!!");
		fclose(fn);
		exit(4);
	}
	while(1)
	{
		ch=fgetc(fne);
		if(ch==EOF)
		{
			break;
		}
		else
		{
			fputc(ch, fn);
		}
	}
	printf(" File %s successfully encrypted ..!!\n\n", fname);
	fclose(fn);
	fclose(fne);
}

#include <stdio.h>

#include <stdlib.h>

void main()

{

//declaring the variable for the program

char fname[20], ch;

FILE *fn, *fne;

printf("\n\n Encrypt a text file :\n");

printf("--------------------------\n");

//taking input from the user

printf(" Input the name of file to encrypt : ");

scanf("%s",fname);

fn=fopen(fname, "r");

if(fn==NULL)

{

printf(" File does not exists or error in opening..!!");

exit(1);

}

fne=fopen("temp.txt", "w");

if(fne==NULL)

{

printf(" Error in creation of file temp.txt ..!!");

fclose(fn);

exit(2);

}

while(1)

{

ch=fgetc(fn);

if(ch==EOF)

{

break;

}

else

{

ch=ch+100;

fputc(ch, fne);

}

fclose(fn);

fclose(fne);

fn=fopen(fname, "w");

if(fn==NULL)

{

//printing the output

printf(" File does not exists or error in opening..!!");

exit(3);

}

fne=fopen("temp.txt", "r");

if(fne==NULL)

{

printf(" File does not exists or error in opening..!!");

fclose(fn);

exit(4);

}

while(1)

{

ch=fgetc(fne);

if(ch==EOF)

{

break;

}

else

{

fputc(ch, fn);

}

printf(" File %s successfully encrypted ..!!\n\n", fname);

fclose(fn);

fclose(fne);

}

Output:-

In the above program, we have first initialized the required variable.

*fn = it will hold the address value.
ch = it will hold the character value.
fname[20] = it will hold the string value of the file name.
*fne = it will hold the address value.

Taking Input file from the user.

Reading the file.

Encrypting the file.

Printing output.

C Program to Get Input from User

In this tutorial, we will learn to create a C program that will Get Input from Users in C programming.

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C programming topics:

Operators in C Programming.
Basic Input and Output function in C Programming.
Basic C programming.

Get Input from the Users

As we all know the program is a collection of different data types. In c programming, we can take the input from the user in various data types. In today’s program, we will take input in many formats. The second will display the data.

With the help of this program, we can Get Input from User

Algorithm 1:-

1. Declaring the variables for the program. 

2. Taking the input from the user in integer format. 

3. Taking the input from the user in float format. 

4. Taking the input from the user in double format. 

5. Printing the data taken in input from the user. 

6. End program.

1. Declaring the variables for the program.

2. Taking the input from the user in integer format.

3. Taking the input from the user in float format.

4. Taking the input from the user in double format.

5. Printing the data taken in input from the user.

6. End program.

Algorithm 2:-

1. Declaring the variables for the program. 

2. Taking the input from the user in character format. 

3. Printing the data taken in input from the user in character format.

4. Printing the data taken in input from the user in ASCII format 

5. End program.

1. Declaring the variables for the program.

2. Taking the input from the user in character format.

3. Printing the data taken in input from the user in character format.

4. Printing the data taken in input from the user in ASCII format

5. End program.

Program to Get Input from User:-

#include <stdio.h>
int main()
{
    //declaring the variable for the program
    int no1;
    float no2;
    double no3;

    //taking input in integer number 
    printf("Enter a integer number: ");
    //Scanning the input by the user
    scanf("%d", &no1);
    //taking input in float number
    printf("Enter a float number: ");
    //Scanning the input by the user
    scanf("%f", &no2);
    //taking input in double number
    printf("Enter a double number: ");
    //Scanning the input by the user
    scanf("%lf", &no3);
    //Printing the output integer value
    printf("no1 = %d\n", no1);
    //Printing the output float value
    printf("no2 = %0.2f\n", no2);
    //Printing the output double value
    printf("no3 = %lf", no3);
    
    return 0;
}

#include <stdio.h>

int main()

{

//declaring the variable for the program

int no1;

float no2;

double no3;

//taking input in integer number

printf("Enter a integer number: ");

//Scanning the input by the user

scanf("%d", &no1);

//taking input in float number

printf("Enter a float number: ");

//Scanning the input by the user

scanf("%f", &no2);

//taking input in double number

printf("Enter a double number: ");

//Scanning the input by the user

scanf("%lf", &no3);

//Printing the output integer value

printf("no1 = %d\n", no1);

//Printing the output float value

printf("no2 = %0.2f\n", no2);

//Printing the output double value

printf("no3 = %lf", no3);

return 0;

}

Program 2:-

#include <stdio.h>
int main()
{
    //declaring the variable
    char chr;
    printf("Enter a character: ");
    scanf("%c", &chr);     

    // When %c is used, a character is displayed
    printf("You entered %c.\n",chr);  

    // When %d is used, ASCII value is displayed
    printf("ASCII value is %d.", chr);  
   
   
    return 0;
}