C++ Comparison of String Literals

Question

I\'m a c++ newbie (just oldschool c). My son asked for help with this and I\'m unable to explain it. If he had asked me \"how do I compare strings\" I would have told hi

Answer 1

String literals have static storage duration. In all these comparisons there are compared addresses of memory allocated by the compiler for string literals. It seems that the first string literal that is encountered by the compiler is stored in memory with a lower address compared with the next encountered string literal.

Thus in this program

int main() 
{ 
  cout << ("Z"< "A");
  cout << ("A"< "Z");
}

string literal "Z" was alllocated with a lower address than string literal "A" because it was found first by the compiler.

Take into account that comparison

  cout << ("A"< "A");

can give different results depending on the options of the compiler because the compiler may either allocate two extents of memory for the string literals or use only one copy of the string literals that are the same.

From the C++ Standard (2.14.5 String literals)

12 Whether all string literals are distinct (that is, are stored in nonoverlapping objects) is implementation defined. The effect of attempting to modify a string literal is undefined.

The same is valid for C.