An example of how to write file in C

fopen-example.c

#include <stdio.h>
#include <string.h>

int main () {

        int ret;
        FILE *fp;
        char filename[] = "/home/user1/file.txt";

        fp = fopen(filename, "w");

        if (NULL == fp) {
                printf("Could not open file for writing\n");
                return 1;
        }

        fprintf(fp, "Here's some content for file.txt");
        fclose(fp);

        return 0;
}