File Handling Examples in C

Example : Write a Program(WAP) in C to create a New Blank File with a File Name and confirm its formation/creation.

#include<stdio.h>
#include<conio.h>

void main()
{ 
    FILE *fp;  // File Pointer declaration(fp) to store the address of first character of file contents  
        
    fp=fopen("D:\\student.txt","w"); 
   
    if(fp==NULL)
    {
        printf("File Does Not Created");
        exit(0); 
    }    
    printf("New Blank File Created Successfully."); 
    
    getch();
}

Output: New Blank File Created Successfully.

NB: New file is created with user given name 'student.txt' in the D drive.

Example : Write a Program(WAP) in C to create a New Blank File with a User-Defined File Name and confirm its formation/creation.

#include<stdio.h>
#include<conio.h>
void main()
{ 
    FILE *fp;
    char filename[30];
 
    printf("\nEnter the File Name You Want to Create : ");
    scanf("%s",filename); 
    
    fp=fopen(filename,"w"); 
   
    if(fp==NULL)
    {
        printf("File Does Not Created");
        exit(0); 
    } 
    printf("New File created successfully."); 
    getch();
}

Output: New File created successfully.

NB: New file is created with user given name in the same directory/drive where the program file(say program1.c) is saved.

Example : Write a Program(WAP) in C to create a new blank file, and then write/store/append Static Data into it.

#include<stdio.h>
#include<conio.h>
int main()
{
    FILE *fp;
    fp = fopen("D:\\New folder\\abc.txt","w");
    fprintf(fp, "Your Popular website is codershelpline for all computer students");
//fprintf(fp, "%s", "Your Popular website is codershelpline for computer students");
    fclose(fp);
    return 0; 
}

NB : Here the static messages 'Your Popular website is codershelpline.com for all computer professionals' is stroed in the newly created "D:\\New folder\\abc.txt" file.

----------------  OR  -----------------

#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{ 
    FILE *fp;
    char filename[30];
 
    printf("\nEnter File Name You Want to Create : ");
    scanf("%s",filename); 
    
    fp=fopen(filename,"w"); 
   
    if(fp==NULL)
    {
        printf("File Does Not Created");
        exit(0); 
    } 
    printf("New File created successfully.");    
    
    putc('C',fp);    //writting single character into file
    putc('H',fp);
    putc('L',fp);
 
    printf("\nData is stored/written in file successfully.\n");
    fclose(fp);
    
    fp=fopen(filename,"r"); 
    printf("Contents of file is/are :\n");
	    
    printf("%c",getc(fp));
    printf("%c",getc(fp));
    printf("%c",getc(fp));
 
    fclose(fp);
    getch();
}

Output :
Enter File Name You Want to Create : abc.txt
New File created successfully.
Data is stored/written in file successfully.
Contents of file is :
CHL

NB: 'Read mode' is used to display the contents of a file whereas 'Write mode' is for Store/Save/Add the contents in the file.

Example : WAP in C to store and display student records in a newly created file.

#include<stdio.h>
#include<conio.h>

void main()
{
    FILE *fp;
    char sname[80],ch;
    int sage;
    float fee;
   
    fp = fopen("student.txt", "w");

    if (fp == NULL)
    {
        printf("File does not exist.\n");
        return;
    }
    
    printf("Enter student name: \n");
    scanf("%s", sname);
    fprintf(fp, "student name  = %s\n", sname);

    printf("Enter student age: \n");
    scanf("%d", &sage);
    fprintf(fp, "student age  is = %d\n", sage);

    printf("Enter student course fee:\n");
    scanf("%f", &fee);
    fprintf(fp, "student fee is  = %.2f\n", fee);

    fclose(fp);
    
    printf("\nThe output is : \n\n");
    
    fp=fopen("student.txt","r");    
    while((ch=getc(fp))!=EOF)
	{
           printf("%c",ch);
        }	      
    fclose(fp) ;
    getch();
}

Output :
Enter student name:
Sohan
Enter student age:
35
Enter student course fee:
501.75

The output is :

student name  = Sohan
student age  is = 35
student fee is  = 501.75

Example : A simple file handling program in C to display the output of already stored file contents.

#include <stdio.h>
#include<conio.h>
void main()
{
    FILE *fp;        
    char ch;     
    fp= fopen ("D:\\New folder\\abc.txt", "r");    
    
    if (fp==NULL)
       {
    	puts("Unable to Open Existing File");
    	exit(0);
       } 
    else 
       {	      
         while(1)
            {
              ch = fgetc(fp);  // To read/extract file contents character by character.
              if(ch==EOF)      // To check the contents of file till the end
                 break;
              else
                 printf("%c", ch);
            }
         }
     fclose(fp);  // To close the file
     getch();
}

/*  ----------  OR  ------------  */

#include<stdio.h>
#include<conio.h> 
void main()
{
  FILE *fp = fopen("F:\\New folder\\abc.txt", "r");
  int ch = getc(fp);  
  while (ch != EOF)
   {
    putchar(ch);
 
    ch = getc(fp);
   }
   
  if (feof(fp))
     printf("\n Now the contents reached the end of file.");
  else
     printf("\n File contents traverse improperly");
     
  fclose(fp);     
  getchar();  
}

Output :
 (NB : First of all 'abc.txt' file contents are displayed and then EOF message on execution the program.) 
 
 This is a codershelpline site for all
 Now the contents reached the end of file.

Example : A file handling program in C to Count the Number of Characters in a file.

#include<stdio.h>
#include<conio.h>
int main()
{
    FILE *fp;
    int count=0;
    char ch;
    fp = fopen("D:\\New folder\\abc.txt","w");
    fprintf(fp, "%s", "Your Popular website is codershelpline.com for all computer professionals");
    fclose(fp);
    
    printf("\nThe Total Characters in the file is : \n\n");
    
    fp=fopen("D:\\New folder\\abc.txt","r");    
    while((ch=getc(fp))!=EOF)
	{
           count++;
        }	      
    fclose(fp) ;
    printf("%d",count);
    return 0; 
}

Output:
The Total Characters in the file is :
73

Example : A file handling program in C to Count the Number of Lines in a file.

#include<stdio.h>
#include<conio.h>
int main()
{
    FILE *fp;
    int count=0;
    char ch;
    fp = fopen("D:\\New folder\\abc.txt","w");
    fprintf(fp, "%s", "Your Popular \nwebsite is codershelpline.com\n for all computer professionals.");
    fclose(fp);    
    
    fp=fopen("D:\\New folder\\abc.txt","r"); 
	   
    //Read character by character to check new line	
	while((ch=fgetc(fp))!=EOF)
	{
		if(ch=='\n')
		   count++;
	}
	fclose(fp);	
	
	printf("Total number of lines are : %d\n",count);
    return 0; 
}

Output:
Total number of lines are : 2

--------------  OR  --------------

#include<stdio.h>
#include<conio.h>
int main()
{
    FILE *fp;
    int count=0;
    char ch;
    fp = fopen("D:\\New folder\\abc.txt","w");
    fprintf(fp, "%s", "This is Your Popular website. It is codershelpline for all computer professionals.");
    fclose(fp);    
    
    fp=fopen("D:\\New folder\\abc.txt","r"); 
	   
    //Read character by character to check new line	
	while((ch=fgetc(fp))!=EOF)
	{
		if(ch=='.')
		   count++;
	}
	fclose(fp);	
	
	printf("Total number of lines are : %d\n",count);
    return 0; 
}
Output: 
Total number of lines are : 2

Example : A file handling program in C to Count the Number of Words in a file.

#include<stdio.h>
#include<conio.h>
int main()
{
    FILE *fp;
    int count=0;
    char ch;
    
    fp = fopen("D:\\New folder\\abc.txt","w");
    fprintf(fp, "%s", "This is Your Popular website.");
    fclose(fp);    
    
    fp=fopen("D:\\New folder\\abc.txt","r"); 
	   
    //Read character by character to check new line	
	while((ch=fgetc(fp))!=EOF)
	{
		if(ch==' ')
		   count++;
	}
	
	fclose(fp);	
	
	printf("Total number of Words are : %d\n",count+1);
    return 0; 
}

Output:
Total number of Words are : 5

Example : WAP in C to create a new file, store data in it, and Rename the created file.

#include <stdio.h>
#include <conio.h>

void main( )
{
    FILE *fp;
    fp = fopen("prg1.c","w");
    fprintf(fp, "%s", "Your website is codershelpline for all computer students");
    fclose(fp);
    
    rename("prg2.c","prg1.c");
    printf("Created/Existing File is Renamed\n");
	 
    fp=fopen("prg1.c","r");
    
    if(fp==NULL)
      {
        printf("File is not Present\n");      
      }	
    else
      {
      	printf("File is Present\n"); 
      }	  
	fclose(fp);     
   getch();       
}
Output:
Created/Existing File is Renamed
File is Present

Example : WAP in C to Remove/Delete a created/existing file.

#include <stdio.h>
#include <conio.h>
#include <string.h>
#include<ctype.h>
 
void main( )
{
   FILE *fp;
    fp = fopen("prg1.c","w");
    fprintf(fp, "%s", "Your website is codershelpline for all computer students");
    fclose(fp);
    
    remove("prg1.c");
    printf("Created/Existing File is Deleted\n");
	 
    fp=fopen("prg1.c","r");
    if(fp==NULL)
      {
        printf("File is not Present\n");      
      }	   
   getch();       
}

Example : How to Copy the contents of one file into another file and display them?

#include <stdio.h>
#include <conio.h>
#include <string.h>
 
void main( )
{
    FILE *fp,*fp1 ;
    char str[500],ch;
	
    fp = fopen("abc.c", "w") ;    //Create a new file & open in write mode.
    printf("Enter the characters for new file below  500\n");
    while (strlen(gets(str))>0)
    {
        fputs(str, fp) ;   
        fputs("\n", fp) ;
    }    
    fclose(fp) ;
    
    fp1=fopen("simple.c","w");    
    fp = fopen("abc.c", "r") ;
    while((ch=fgetc(fp))!=EOF)
	{        
	   putc(ch,fp1);
           //fputc(ch,fp1);
        }    
    fclose(fp) ;
    fclose(fp1) ;
	
    fp1=fopen("simple.c","r");  
    printf( "The copied values are :\n" ) ;
    while((ch=getc(fp1))!=EOF)
	{
           printf("%c",ch);
        }	      
    fclose(fp1) ;	   
   getch();       
}

NB: Press two time Enter button to stop to take input below 150 characters.

Example : How do you convert lowercase letters in one file into uppercase letters in another and display them?

#include <stdio.h>
#include <conio.h>
#include <string.h>
 
void main( )
{
    FILE *fp,*fp1 ;
    char str[150],ch;
	
    fp = fopen("abc.c", "w") ;    //Create a new file & open in write mode.
    printf("Enter the characters for new file below  150\n");
    while (strlen(gets(str))>0)
    {
        fputs(str, fp) ;   
        fputs("\n", fp) ;
    }    
    fclose(fp) ;
    
    fp1=fopen("simple.c","w");    
    fp = fopen("abc.c", "r") ;
    while((ch=fgetc(fp))!=EOF)
	{        
	  if(islower(ch))
	    {
               ch=ch-32; 
            }        
	   putc(ch,fp1);                       
        }    
    fclose(fp) ;
    fclose(fp1) ;
	
    fp1=fopen("simple.c","r");  
    printf( "The outputs are \n" ) ;
    while((ch=getc(fp1))!=EOF)
     {
        printf("%c",ch);
     }	      
    fclose(fp1) ;	   
   getch();       
}

Example :  How do you Merge two files’ contents into another file and display them?

#include <stdio.h>
#include <conio.h>
#include <string.h>
 
void main( )
{
    FILE *fp1,*fp2,*fp3 ;
    char str1[150],str2[150],str3[300],ch;
	
    fp1 = fopen("abc.c", "w") ;    //Create a new file & open in write mode.
    printf("Enter the characters in first file below  150 size\n");
    while (strlen(gets(str1))>0)
    {
        fputs(str1, fp1) ;   
        fputs("\n", fp1) ;   //sends cursor in new line after insertion of newline characters. 
    }    
    fclose(fp1) ;
    
    fp2 = fopen("simple.c", "w") ;    //Create a new file & open in write mode.
    printf("Enter the characters in second file below  150 size\n");
    while (strlen(gets(str2))>0)
    {
        fputs(str2, fp2) ;   
        fputs("\n", fp2) ;
    }    
    fclose(fp2) ; 
	   
    fp3=fopen("xyz.c","w");
    
    fp1=fopen("abc.c","r");    
    while((ch=fgetc(fp1))!=EOF)
	{        
	   putc(ch,fp3); 
        }    
    fclose(fp1) ;
    
    fp2=fopen("simple.c","r");    
    while((ch=fgetc(fp2))!=EOF)
	{        
	   putc(ch,fp3); 
        }    
    fclose(fp2) ;
    
    fclose(fp3) ;
	
    fp3=fopen("xyz.c","r");  
    printf( "The merged values of two files are :\n") ;
    while((ch=getc(fp3))!=EOF)
	{
           printf("%c",ch);
        }	      
    fclose(fp3) ;	   
   getch();       
}

Output :
Enter the characters in first file below  150 size
www.codershelpline.com
Enter the characters in second file below  150 size
It is a very good site for computer knowledge.

The merged values of two files are :
www.codershelpline.com
It is a very good site for computer knowledge.

Example :  How do you display the Reverse of file contents?

#include <stdio.h>

int main() 
{
    FILE *fp;
    long file_size;
    char ch;
    long i;

    fp = fopen("example.txt","w");
    fprintf(fp, "Your Popular website is codershelpline for all computer students");
    fclose(fp);
	
    fp = fopen("example.txt", "r"); // Open file in read mode
    if (fp == NULL) 
      {
        printf("Error in opening file.\n");
      } 
    else 
      {
        fseek(fp, 0, SEEK_END); // Move to end of file
        file_size = ftell(fp);  // Get the size of the file stored on the disk

        for (i = file_size - 1; i >= 0; i--) 
         {
            fseek(fp, i, SEEK_SET);  // Move pointer to specific position
            ch = fgetc(fp);  // Read character
            printf("%c", ch);  // Print in reverse order
         }
        fclose(fp);  // Close the file
      }
    return 0;
}

Output: stneduts retupmoc lla rof enilplehsredoc si etisbew ralupoP ruoY

Example :  How do you get the Size of the File stored on the disk?

#include <stdio.h>

int main() 
{
    FILE *fp;
    long file_size;    

    fp = fopen("example.txt","w");
    fprintf(fp, "Your Popular website is codershelpline for all computer students");
    fclose(fp);
	
    fp = fopen("example.txt", "r"); // Open fp in read mode

    if (fp == NULL) 
    {
        printf("Error in opening file.\n");
    } 
    else 
    {
    // Move the file pointer to the end of the file
    fseek(fp, 0, SEEK_END);
		
    file_size = ftell(fp);  // Get the size of the file stored on the disk
    printf("The size of file on the disk is %ld bytes",file_size);
			        
    fclose(fp);  // Close the file
    }

    return 0;
}

Output: The size of file on the disk is 64 bytes.

NB: The program uses 'fseek' to jump to the end of the file and 'ftell' to get the position of the file pointer, which indicates the size of the file.

Example : A file handling program in C to display its own written source code on the screen as output.

#include <stdio.h>
int main() 
{
    FILE *fp;
    int ch;
    fp = fopen(__FILE__,"r");
    do 
    {
         ch = getc(fp);
         putchar(ch);
    }
    while(ch != EOF);
    fclose(fp);
    return 0;
}

NB :This program displays the content of file source code due to use of __FILE__ that contains the location of this C programming file in a string.