string - krishnaramb/cplusplus GitHub Wiki
string substr (size_t pos = 0, size_t len = npos) const;
Returns a newly constructed string object with its value initialized to a copy of a substring of this object.
The substring is the portion of the object that starts at character position pos and spans len characters (or until the end of the string, whichever comes first).
// comparing apples with apples
#include <iostream>
#include <string>
int main ()
{
std::string str1 ("green apple");
std::string str2 ("red apple");
if (str1.compare(str2) != 0)
std::cout << str1 << " is not " << str2 << '\n';
if (str1.compare(6,5,"apple") == 0)
std::cout << "still, " << str1 << " is an apple\n";
if (str2.compare(str2.size()-5,5,"apple") == 0)
std::cout << "and " << str2 << " is also an apple\n";
if (str1.compare(6,5,str2,4,5) == 0)
std::cout << "therefore, both are apples\n";
return 0;
}