// bad/missing length/position
An unsigned integral value initialized to –1 that indicates either "not found" or "all remaining characters" when a search function fails.
static const size_type npos = -1;
Example
#include "stdafx.h"
#include <iostream>
#include <string>
int main()
{
std::string input = "input
string";
if (input.find('b') == std::string::npos)
{
std::cout
<< "no 'b' found
in 'input string'\n";
}
if (input.find('p') != std::string::npos)
{
std::cout
<< "'p' found in
'input string'\n";
}
}