Parsing int in C++11 - stoi

Question

I am trying to take a string and parse it into an int. I have read the many answers out there, and it seems that using stoi is the most up-to-date way. It appears to me that stoi uses std, but I am getting Function 'stoi' could not be resolved despitre using namespace std;

#include <iostream>
#include <string>
#include <cstring>
#include <fstream>
#include<stdlib.h>

using namespace std;

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

    string line = "";
    string five = "5";
    int number = stoi(five); //Error here with stoi
    return 0;
}

Any ideas what is causing this?

Update:

I am using Eclipse. My flags are: -c -fmessage-length=0 -std=c++11

You forgot to tell us which is your compiler, and how you are compiling this program. — Lightness Races in Orbit, Jan 25 '14 at 18:03
plab nice find plab. good eye! post that in your answer for a big green check mark — Evorlor, Jan 25 '14 at 18:10
You still haven't told us what compiler, what version, or anything like that. Please get into the habit of being _precise_. — Lightness Races in Orbit, Jan 25 '14 at 18:17
Personally I like stringstream for this case. `istringstream iss(five); iss >> number;` — Brandin, Jan 25 '14 at 19:13

score 2 · Answer 1 · edited May 23 '17 at 11:44

If you are using GCC or MINGW, then this is the answer: std::stoi doesn't exist in g++ 4.6.1 on MinGW

This is a result of a non-standard declaration of vswprintf on Windows. The GNU Standard Library defines _GLIBCXX_HAVE_BROKEN_VSWPRINTF on this platform, which in turn disables the conversion functions you're attempting to use. You can read more about this issue and macro here: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37522.

If you're willing to modify the header files distributed with MinGW, you may be able to work around this by removing the !defined(_GLIBCXX_HAVE_BROKEN_VSWPRINTF) macro on line 2754 of .../lib/gcc/mingw32/4.6.1/include/c++/bits/basic_string.h, and adding it back around lines 2905 to 2965 (the lines that reference std::vswprintf). You won't be able to use the std::to_wstring functions, but many of the other conversion functions should be available.

Please always provide platform and compiler information.

score 0 · Accepted Answer · edited May 23 '17 at 11:52

0

Toggle on C++11 support in your compiler flags. -std=c++11 for a recent gcc. For Eclipse, please refer to the corresponding question in the FAQ and this answer explains how to get rid of the remaining Eclipse warning.

edited May 23 '17 at 11:52

Community

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answered Jan 25 '14 at 18:02

user3146587

4,250
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Cool thanks. Know the name of the file by any chance? I am running it in Eclipse at the moment. – Evorlor Jan 25 '14 at 18:03
@Evorlor: The name of what file? – Lightness Races in Orbit Jan 25 '14 at 18:03
I am not actually compiling this in the terminal. I am coding this in Eclipse. – Evorlor Jan 25 '14 at 18:04
@plabatut Hmmm...thank you, but that did not appear to solve the problem – Evorlor Jan 25 '14 at 18:07
@Evorlor Note that eclipse is an IDE; It doesn't actually compile your programs (at least not to get an executable, for the pedantic). For that, it will invoke an external compiler just like you would on the terminal. – Cubic Jan 25 '14 at 18:31

score 0 · Answer 3 · answered Jan 25 '14 at 21:18

0

If you are amenable to parsing an int another way, how about using an STL algorithm and a C++11 lambda expression?

#include <algorithm>
#include <iostream>
#include <string>

using namespace std;

int main() {
    string str = "12345";

    int num = 0;

    for_each(str.begin(), str.end(), [&num](char c){ num = 10 * num + (c - '0');  });

    cout << str << " = " << num << endl;
}

answered Jan 25 '14 at 21:18

user3236204

1

Good catch! I think the { int number; istringstream iss("5"); iss >> number; } approach suggested by Brandin is more general and suitable. – user3236204 Jan 26 '14 at 12:41

Parsing int in C++11 - stoi

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