1. Đọc ghi file

1.1 Đọc file

int main()
{
    int n;
    FILE *f = fopen("cow4.inp", "r");    // mo file de ghi
 
    if(f != NULL) {
        fscanf(f, "%d", &n);
        fclose(f);
    } else {
        printf("Loi doc file");
    }

    return 0;
}

1.2 Ghi file

#include <stdio.h>
 
int main()
{
    int n = 10;                      // khai bao bien ten
    FILE *f = fopen("output.txt", "w");    // mo file de ghi
 
    if(f != NULL) {
        fprintf(f, "%3d", n);
     
        fclose(f);     // dong file fo
    } else {
        printf("Khong doc duoc file!");
    }
        
    return 0;
}