Run-Time Check Failure #2 - Stack around the variable 'd' was corrupted. (C programming under Visual Studio)

Question

Hello I am new here and programming in C. I didn't want to ask something that you may consider simple but I have asked my classmates and even my programming teacher to see if they can find the error but until today they couldn't find it (them).

But first let me describe what I know, it says:

"Run-Time Check Failure #2 - Stack variable "d" (and sometimes m and other y) was corrupted ".

I made my job trying to debug it but the problem is always showed on the last codeline (of the main body), so I couldn't find exactly where the problem is, here I attach the code, and I would be very happy if you find the problem and explain me the reason why I get it (to don't repeat the same mistakes in future) =D.

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

/* Type Declaration */
#define true 1
#define false 0
typedef char boolean;

/* Functions declaration */

boolean test( short int d, short int m, long int y );
boolean nextday( short int d, short int m , long int y );

int main( void )
{
    /* Variables initialization */
    short int d = 0, m = 0; 
    long int y = 0;

    do {
        /* Data by user*/
        printf( "Ingrese el numero de año: " );
        scanf( "%ld", &y );
    }   while ( y < 0 );

    do {
        printf( "Ingrese el numero de mes: " );
        scanf( "%d", &m );  
    }   while ( m < 1 || m > 12 );

    do {
        printf( "Ingrese el numero de dia: " );
        scanf( "%d", &d );
    }   while ( d < 01 || ( test( d, m, y ) == false ) ); // If the data is wrong then re-type the data


    // If the nextday function return value is true then the next day is 01, if not just sum a day
    if ( nextday ( d, m, y ) == true ) { 
        d = 01;

        // If we start a new year the new month must be 01-01-01.
        if ( m == 12 ) {
            m = 01;
            y++;
        }

        // Just increase the month for any other month
        else {
            m++;
        }
    }

    else {
        d++;
    }

    printf( "Mañana será: %d-%d-%ld\n", d, m, y );

    return 0;
}

boolean test( short int d, short int m, long int y ){
    int max;

    switch(m) {
        case 1:       
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            max = 31;
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            max = 30;
            break;
        case 2:
            if ( y % 400 == 0 ){
                max = 29;
            }
            else if ( y % 100 == 0 ){
                max = 28;
            }
            else if ( y % 4 == 0 ){
                max = 29;
            }
            else {
                max = 28;
            }
            break;
    }
    if ( d <= max ){
        return true;
    }
    else {
        return false;
    }
}

boolean nextday( short int d, short int m, long int y ) {

    boolean x;

    // If it's 28-02 in a secular year * 4 then it's a leap-year. (so it has 29 days)
    if  ( m == 2 && d == 28 && y % 400 == 0 ) {
        x = false;
    }

    // If it is an end of century but it isn't 4 multiply then it only has 28 days.
    else if ( m == 2 && d == 28 && y % 100 == 0 ) { 
        x = true;
    }

    // If it just a leap year it has 29 days.
    else if ( m == 2 && d == 28 && y % 4 == 0 ) { 
        x = false;
    }

    //If it's the last day of February and it's a leap year.
    else if ( m == 2 && d == 29 && y % 4 == 0 ){
        x = true;
    }

    // If we are in the end of the month.
    else if ( ( d == 30 && ( m == 4 || m == 6 || m == 9 || m == 11 ) ) || 
                d == 31 ) {  
        x = true;
    }

    // Then if it is another day just sum a day
    else {
        x = false;
    }

    return x;
}

Answer 1

scanf( "%d", &m );  

%d means "this argument points to an int." You are providing a pointer to a short int. Either use %hd (for short int) or, preferably, change m to type int (why bother with short int here?).

Answer 2

You need to use:

scanf( "%hd", &m );
scanf( "%hd", &d );

since they are short int's.

Using "%d" you are basically loading an int size variable in a small int storage space.

An int is usually 4 bytes while small int is 2 bytes.