fsetpos() (Set File Position) in C

The fsetpos() function moves the file position indicator of the given file stream to the specified position. When fsetpos() is executed, the end-of-file indicator is reset. fsetpos() function is a part of <cstdio> header file in C Standard Library.

Syntax of fsetpos()

int fsetpos(FILE *stream, const fpos_t *pos)

Parameters

• stream – This is the pointer to a FILE object that identifies the stream.
• position – This is the pointer to a fpos_t object containing the desired value of the position indicator.

Return Value

• If it is successful, it returns zero otherwise returns a nonzero value.

C Program to Illustrate the use of fsetpos()

C

// C program to illustrate the use of fsetpos()
#include <stdio.h>

int main()
{
    // File pointer
    FILE* fp;
    // Variable to store file position
    fpos_t position;

    // Open file in write and read mode
    fp = fopen("myfile.txt", "w+");

    // Get current file position and store it
    fgetpos(fp, &position);

    // Write "HelloWorld!" to the file
    fputs("HelloWorld!", fp);

    // Set file position back to the stored position
    fsetpos(fp, &position);

    // Write "geeksforgeeks" to the file from the restored
    // position
    fputs("geeksforgeeks", fp);

    // setting file pointer position back to the stored
    // position
    fsetpos(fp, &position);

    // storing data stored in file
    char arr[50];
    fgets(arr, 14, fp);

    // printing output
    puts(arr);

    // Close the file
    fclose(fp);

    return (0);
}

Output

geeksforgeeks