Why passing pointer to a function lead to a Runtime Error?

Question

I'm trying to understand how passing pointers to functions work, but I don't understand the following situation : Why this code work

void setVar(uint32_t* var) {
    *var = 10;
} 

int main() {
    uint32_t myVar = 0;
    setVar(&myVar);

    return 0;
}

and this one lead to a runtime error ? :

void setVar(uint32_t* var) {
    *var = 10;
} 

int main() {
    uint32_t* myVar = 0;
    setVar(myVar);

    return 0;
}

I'd appreciate your answers.

Answer 1

The issue is not the pointer. The issue is that you initialize the pointer you pass to the function with 0 (uint32_t* myVar = 0;) and then dereference it in your function (*var = 10;), which is disallowed. You should make sure, the pointer that is passed is not a NULL pointer, either do that within the function or make sure that function only ever is called with valid parameters.