Which issues have you encountered due to sequence points in C and C++?

Question

Below are two common issues resulting in undefined behavior due to the sequence point rules:

a[i] = i++; //has a read and write between sequence points
i = i++;          


        

Answer 1

There are some ambigous cases concerning the order of execution in parameter lists or e.g. additions.

#include 

using namespace std;

int a() {
    cout << "Eval a" << endl;
    return 1;
}

int b() { 
    cout << "Eval b" << endl;
    return 2;
}

int plus(int x, int y) {
    return x + y;
}

int main() {

    int x = a() + b();
    int res = plus(a(), b());

    return 0;
}

Is a() or b() executed first? ;-)