Convert iterator to int

Question

int i;
vector<string> names;
string s = "penny";
names.push_back(s);
i = find(names.begin(), names.end(), s);
cout << i;

I'm trying to find index of an element in vector. It's ok with iterators, but I want it as int. How can I do it?

Answer 1

You can use std::distance for this.

i = std::distance( names.begin(), std::find( names.begin(), names.end(), s ) );

You will probably want to check that your index isn't out of bounds, though.

if( i == names.size() )
    // index out of bounds!

It's probably clearer to do this with the iterator before using std::distance, though.

std::vector<std::string>::iterator it = std::find( names.begin(), names.end(), s );

if( it == names.end() )
     // not found - abort!

// otherwise...
i = std::distance( names.begin(), it );

Answer 2

std::vector<string>::iterator it = std::find(names.begin(), names.end(), s);
if (it != names.end()) {
    std::cout << std::distance(names.begin(), it);
} else {
    // ... not found
}