Possible Duplicate:
How can I convert string to double in C++?
how can I cast string to double in c++?
I have a string vector with numbers in it and i want to copy it into a vector of type double
while (cin >> sample_string)
{
vector_string.push_back(sample_string);
}
for(int i = 0; i <= vector_string.size(); i++)
{
if(i != 0 && i != 2 && i != vector_string.size()-1)
vector_double.push_back((double)vector_string[i]);
}
edit: i cant use BOOST
I think you should use the stringstream class provided with the STL. It enables you to convert from string to double and the other way around. Something like this should work:
#include <sstream>
string val = "156.99";
stringstream s;
double d = 0;
s << val;
s >> d;
Assuming you have boost installed,
{
using boost::lexical_cast;
vector_double.push_back(lexical_cast<double>(vector_string[i]));
}
Assuming you don't have boost installed, add this function template, and invoke it:
template <class T1, class T2>
T1 lexical_cast(const T2& t2)
{
std::stringstream s;
s << t2;
T1 t1;
if(s >> t1 && s.eof()) {
// it worked, return result
return t1;
} else {
// It failed, do something else:
// maybe throw an exception:
throw std::runtime_error("bad conversion");
// maybe return zero:
return T1();
// maybe do something drastic:
exit(1);
}
}
int main() {
double d = lexical_cast<double>("1.234");
}
Boost (among others) provides a lexical_cast for exactly your purpose.
