Example 1 demonstrates the principle of least surprise as follows:

#include <iostream>

int sub(int a, int b)
{ return a + b; }

int main(void)
{
    std::cout << "The answer is: " << sub(41, 1) << '
';
    return 0;
}

As shown in the preceding example, we have implemented a library API that adds two integers and returns the results. The problem is that we named the function sub, which most developers would associate with subtraction and not addition; although the API functions as designed, it breaks the principle of least surprise because the API's name is not intuitive.