Question

The following code compiles without any warning or error on G++ (GCC) 4.1.2.

Is there a reason for not issuing an error/warning?

Is there a flag that can cause it to issue a warning or error?

#include <iostream>

using namespace std;

void func(string &s)
{
    unsigned long u = 123;
   s = u;
}

int main()
{
   string s;

   func (s);

   return 0;
}

Answer 1

The reason there’s no warning or error is because this is valid C++. std::string overloads the assignment operator (operator=) to take a char. long can be implicitly converted to a char, hence the code makes sense.