++i and i++ in while loop in C

I am using a program to detect the boundary of each data type, which is like this:

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

int main()
{
    /*first while loop using a++ dosesn't give us a right answer*/
    int a = 0;
    while (a++ > 0);
        printf("int max first = %d\n", a-1);

    /*second while loop using ++a performs well*/
    int b = 0;
    while (++b > 0);
        printf("int max second = %d\n", b-1);

    system("pause");
    return 0;
}

After I compile this propram and excute it, it returns:

int max first = 0
int max second = 2147483647

So I try to debug it, and I find out that in the first part, after a++ becomes 1, then it just stop autoincrement and jump the while loop，while in second part it runs well, why is this happening?