basic_string::compare

int compare(const basic_string& str) const;
int compare(size_type p0, size_type n0,
    const basic_string& str);
int compare(size_type p0, size_type n0,
    const basic_string& str, size_type pos, size_type n);
int compare(const E *s) const;
int compare(size_type p0, size_type n0,
    const E *s) const;
int compare(size_type p0, size_type n0,
    const E *s, size_type pos) const;

Each member function compares up to n0 elements of the controlled sequence beginning with position p0, or the entire controlled sequence if these arguments are not supplied, to the operand sequence. The function returns:

• A negative value if the first differing element in the controlled sequence compares less than the corresponding element in the operand sequence (as determined by T::compare), or if the two have a common prefix but the operand sequence is longer.
• Zero if the two compare equal element by element and are the same length.
• A positive value otherwise.