Can anybody explain why this code will not run?

Question

C language
https://code.sololearn.com/cVS8MJKz2X31/?ref=app

Answer 1

#include <stdio.h>
int a, b, c;
// if you dont provide function prototype , then add function defination before using..
void small(int x, int y, int z) // must provide return type for all functions..
{

x=x+1;
y=y+1;
z=z+1;
printf("%d%d%d\n",x,y,z);
}

void medium(int *x, int *y, int *z)
{
*x=*x+1;
*y=*y+1;
*z=*z+1;
}

void large(int *x, int *y, int *z)
{
*x=*x+1;
*y=*y+1;
*z=*z+1;
printf("%d%d%d\n",*x,*y,*z);
small(*z,*x,*y);
}

int main() // must provide return type
{
//clrscr(); // dont work here
a=1; b=2; c=3;
printf("%d%d%d\n",a,b,c);
small(a,b,c);
printf("%d%d%d\n",a,b,c);
medium(&c,&b,&a);
printf("%d%d%d\n",a,b,c);
large(&b,&c,&a);
printf("%d%d%d\n",a,b,c);
large(&b,&c,&a);
printf("%d%d%d\n",a,b,c);
//getch(); // dont work , deprecated
}