Save into file C

#include <stdio.h>
#include <stdlib.h>

int main()
{
    char TestMas[10] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
    FILE *MasTest = fopen("LetsTestTheseMas.txt", "w+a");
    char i='7';

        putc(i,MasTest );

    putc('\n', MasTest);
    fclose(MasTest);
    return 0;
}