Thread: strtol() is the only way?

I'm trying to grab a C++ style string and fill a vector<unsigned int> with the same size as the string has characters. Each character on the string is a number from 0 to 9. As such the vector will have ints ranging from 0 to 9.

Follows a piece of the code with a literal string for testing purposes.

Code:

int strto_int (const string &str) {
    const char *pstr = str.c_str();
    char *pend;
    return static_cast<int>( strtol(pstr, &pend, 0) );
}

int main()
{
    string frame = "123423544126673467372411345223672338990";
    vector<unsigned int> vframe;

    for (string::size_type i = 0; i != frame.size(); ++i)
        vframe.push_back( strto_int(frame.substr(i, 1)) );
}

My question relates to strtol(). I couldn't find any other way to convert. It seems to me though excessive to have to convert a C++-style string to a C-style string because I can only use C-style function to do some work on that C++ string. Is strtol() really the only way to convert? Or am I missing something on the STL?

>Or am I missing something on the STL?
Well, technically it's not a part of the STL. You're looking for std::stringstream. The FAQ has info on how to use it. Or if that's too verbose for you, Boost has a lexical_cast template that works nicely.

Originally Posted by Prelude

You're looking for std::stringstream.

Ahh, streams. Still have to learn about those. Thanks Prelude.

Originally Posted by Kurt

vframe[i] = frame[i]-'0';

Loved it!
But you really need to help me understand what you are doing in there

Ascii codes. Got it!