I'm currently trying to take a string ("0.1") and convert it to a double using C++ in Xcode on 10.6 with gcc4.2.

I'm using a function I pinched from [another question](https://stackoverflow.com/questions/392981/how-can-i-convert-string-to-double-in-c), but when I try to use the function, my input according to gdb is (string)"0.1", but my output is (double)2.1220023981051542e-314.

Here is my snippet copied straight out the code:

```
double strToDouble(std::string const &numberString)
{
    istringstream inStream(numberString);
    double doubleValue;
    inStream >> doubleValue;
    if(!(inStream && (inStream >> std::ws).eof()))
    {
        return 0.0;  
    }

    return doubleValue;
};

```

I'm using C++ rather than Obj-C, as it will probably have to be compiled on a \*nix or windows machine eventually.

I'm naturally a PHP programmer, but have some number crunching I need to speed up, so I'm doing it in a compiled language. It's been a long time since University dealing with a lower level language =P. So, if anyone has an ideas, it would be greatly appreciated...

Drew J. Sonne.

Full code:

```
#include <iostream>
#include <vector>
#include <string>
#include <sstream>
using namespace std;

/*
 * @var delimiters the string to define a break by
 * @var str the string to break
 * @var tokens where to store the broken string parts.
 */
void explode(const string& delimiters, const string& str, vector<string>& tokens)
{
    // Skip delimiters at beginning.
    string::size_type lastPos = str.find_first_not_of(delimiters, 0);
    // Find first "non-delimiter".
    string::size_type pos     = str.find_first_of(delimiters, lastPos);

    while (string::npos != pos || string::npos != lastPos)
    {
        // Found a token, add it to the vector.
        tokens.push_back(str.substr(lastPos, pos - lastPos));
        // Skip delimiters.  Note the "not_of"
        lastPos = str.find_first_not_of(delimiters, pos);
        // Find next "non-delimiter"
        pos = str.find_first_of(delimiters, lastPos);
    }
};

/*
 * @var numberString double to be converted as a string.
 */
double strToDouble(std::string const &numberString)
{
    istringstream inStream(numberString);
    double doubleValue;
    inStream >> doubleValue;
    if(!(inStream && (inStream >> std::ws).eof()))
    {
        return 0.0;  
    }

    return doubleValue;
};

class Cluster {
private:
    vector<double> latStore;
    vector<double> lngStore;
public:
    Cluster(int,string,string);
};

/*
 * @var latString a comma seperated list of doubles for the latitudes.
 * @var lngString a comma separated list of doubles for the longitudes.
 */
Cluster::Cluster(int newLocationLength, string latString, string lngString)
{
    // mark our vectors
    vector<string> latStoreString;
    vector<string> lngStoreString;

    // Explode our input strings.
    explode(",", latString, latStoreString);
    explode(",", lngString, lngStoreString);

    for( int i = 0; i < latStoreString.size(); i++)
    {
        // Grab the latitude and store it.
        string tempLat = latStoreString[i];
        double latDouble = strToDouble(tempLat);
        latStore.push_back( strToDouble(tempLat) );

        // Grab the longitude and store it.
        string tempLng = lngStoreString[i];
        lngStore.push_back( strToDouble(tempLng) );
    }
}

int main (int argc, char * const argv[]) {

    Cluster *rect = new Cluster("0.1,0.4","0.1,0.4");

    return 0;
}

```