Question

Hey all. I wrote this program for an online contest. It RUNS FINE on Bloodshed’s Dev-C++ but it breaks down with GCC. The contest demands all solutions based on GCC compiler.

It doesn’t even wait for the 2nd input. The program worked fine on Dev-C++. Please, help.

#include <stdio.h>

int testCases;

void runPgm()
{
    scanf("%d", &testCases);
    int array[testCases][2];
    char start[testCases];
    int i;
    for(i=0; i<testCases; i++)
    {
        scanf("%c %d %d", &start[i], &array[i][0], &array[i][1]);
    }
    for(i=0; i<testCases; i++)
    {
        printf("%c %d %d\n", start[i], array[i][0], array[i][1]);
    }
}

int main() {
    runPgm();
    return 0;
}

Output with GCC:

machine:~$ cc prog.c -lm  
machine:~$ ./a.out  
2
a 3 3

 0 -1080493616
a 3 3
machine:~$

Answer 1

After getting “testCases”, you use the “Enter” key, which adds “\n” to the buffer.

You should use getchar() to get the “\n” out of the buffer. same thing for the scanf in the for loop

Your fixed code:

#include <stdio.h>
int testCases;


void runPgm()
{
    scanf("%d", &testCases);
    getchar();

    int array[testCases][2];
    char start[testCases];
    int i;
    for(i=0; i<testCases; i++)
    {
        scanf("%c %d %d", &start[i], &array[i][0], &array[i][1]);
        getchar();
    }
    for(i=0; i<testCases; i++)
    {
        printf("%c %d %d\n", start[i], array[i][0], array[i][1]);
    }
}

int main() {
    runPgm();
    return 0;
}

BTW,
defining arrays like you did, is not ANSI-C compatible, and I am not sure why gcc is ok with this. You should use dynamic allocation for that purpose (like malloc())