Thread: string to int

Yes. Because the way atoi works is... strange... to be nice to it and more often than not forces code to be written in order to tame it.

atoi("12 - Hello Mum!") will gladly be converted to 12.
and atoi("What a wonderful strange thing to return") will gladly return 0.

http://faq.cprogramming.com/cgi-bin/...wer=1046996179 for more control on the conversion.

> One more thing, what would be the right way to catch exception?
Baseball gloves - exceptions travel at a heck of a speed, so you need something with padding

Originally Posted by l2u

Hey..

Heres my version of string convertion:

Code:

template <class t>
t string_convert(const string &s) {
	istringstream stream(s);
	t i;

	if (stream >> i)
		return i;

	return 0;
}

I call it with
int i = string_convert<int>(some_string);

But I get link error.. No idea why..

There is no way that's going to work because the compiler doesn't know what type to return. Try passing in a argument to your template func.

Code:

template <class T>
void string_convert(const std::string &str, T &myVar)
{
    .. code here
    myVar  = str converted to T
}

EDIT: nvm, I would use the stringstream option if i had to do this
EDIT2: I may and probably am wrong about the compiler not knowing what type to return (that is specified by T), however I can say that returning 0 in ALL cases is probably not appropriate.
EDIT3: Bah, I had to get this working here's the code I came up with:

Code:

#include <iostream>
#include <string>
#include <sstream>

template <class T>
T string_convert(const std::string &s) {
	std::istringstream stream(s);
	T i;

	if (stream >> i)
		return i;

	return 0;
}

int main()
{
    std::string myStr("12345");
    
    std::cout << string_convert<int>(myStr);
    return 0;
}