Question

How to use fseek() function to read specific numbers from binary filein C

Answer 1

#include <stdio.h>
 
int main(int argc, char **argv) 
{ 
    FILE *f;
    int n;

    f = fopen("d:\\data.bin", "rb");
    if (!f)
    {
        printf("Unable to open d:\\data.bin");
        return 1;
    }
    // SEEK_SET - offset is relative to the beginning of the file
    fseek(f, sizeof(int) * 2, SEEK_SET); 
    fread(&n, sizeof(int), 1, f);
    printf("%d\n", n);
    
    fseek(f, sizeof(int) * 5, SEEK_SET);
    fread(&n, sizeof(int), 1, f);
    printf("%d\n", n);
    
    fclose(f);
     
    return(0);
}
 
/*

(in file we have the numbers: 1 2 3 4 5 6 7 8 9 10)

run:
 
3
6

*/

 

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