Thread: Writing functions to prove that variables cannot be changed by another function.

It is said that variables in a function cannot be changed by another function. Only by using pointers can variable values be changed.

I am writing some functions to try to prove this theory, but I can't get it right.

Code:

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

int main(void)
{
    int x = 10;
    printf("default x value is %d\n",x);
    try1(x);
    printf("x after try1 is %d\n", x);
    try2(&x);
    printf("x after try2 is %d\n", x);
    
    return 0;
}

Code:

#include <stdio.h>

void try1(int x){
    printf("x in try1 is %d\n", x);
    x++;
    printf("x in try1 after ++ is %d\n", x);
}

void try2(int *x){
    printf("x in try2 is %d\n", *x);
    *x++;
    printf("x in try2 after ++ is %d\n", *x); // Error, always gives me the address memory number
}