i am getting an problem
string ccc="example"; int cc=atoi(csession); it says cannot convert ‘std::string’ to ‘const char*’ for argument ‘1’ to ‘int atoi(const char*)’ do i should convert the string to char array and then apply to atoi or is there is any other way
istringstream in(ccc); int cc; in >> cc; if(in.fail()) { // error, ccc had invalid format, more precisely, ccc didn't begin with a number //throw, or exit, or whatever } istringstream is in header <sstream> and in namespace std. The above code will extract the first integer from the string that is, if ccc were "123ac" cc would be 123. If ccc were "abc123" then cc would have undefined value and in.fail() would be true.
atoi is better IMHO."abc" is caught!"000". And that's just the first thing I could think of. Face it, doing this using the C std lib is hard for beginners, doing it using the C++ std lib (i.e. using string streams) is much easier. And the speed is rarely ever needed. Premature optimization is the root...According to your description, maybe what you want is:
string ccc="example"; int cc=atoi(ccc.c_str());
Use .c_str() on the string object to pass it to atoi
Hehe, nice one Armen. Here's a solution using boost::lexical_cast:
#include <boost/lexical_cast.hpp> . . . int c = boost::lexical_cast<int>(csession); Documentation available here: boost::lexical_cast.
+1 from me. If you haven't installed boost yet, go ahead and do so.