FILE HANDLING

In programming, we may require some specific input data to be generated several numbers of times. File Handling in C enables us to create, update, read, and delete the files stored on the local file system through our C program. 

The following operations can be performed on a file

1. Creating a new file.
2. Opening an existing file.
3. Closing a file.
4. Reading from and writing to a file.

OPENING and CLOSING A FILE-

Opening a file is performed using the fopen() function defined in the stdio.h header file. Closing a file is performed using the fclose() function. 

Example:-

ptr = fopen("fileopen", "mode");                                //for opening

fopen("E:\\cprogram\\newprogram.txt", "w");            //for opening

fclose(fptr);    // for closing

READING and WRITING A FILE-

For reading and writing to a text file, we use the functions fprintf()  and fscanf(). These functions just file versions of printf() and scanf(). 

Writing a file

#include<stdio.h>

void main()

{

FILE *fp;

fp = fopen("file.txt", "wt");

fprintf(fp, "Thisis testing for fprintf....\n");

fputs("This is testing for fputs..\n", fp);

fclose(fp);

}

The function fputs() writes the string s to the output stream referenced by fp. It returns a non-negative value on success, otherwise EOF is returned in case of any error.

Reading a file

#inlcude<stdio.h>

int main()

{

FILE *fp;

char str[60];

fp = fopen("file.txt", "r");

if(fp == NULL)

{

perror("error opening file");

return(-1);

}

if(fgets(str, 60, fp)!=NULL)

{

puts(str);

}

fclose(fp);

return(0);

}

The fgetc() function reads a character from the input file referenced by fp. The return value is the character read, or in case of any error, it returns EOF.