Does libstdc++ not implement std::stoi?

问题:

I want to use std::stoi. Although I could use ::atoi(str.c_str()) it would make the code cleaner if this would work. But Eclipse tells me:

Function 'stoi' could not be resolved

I checked that

• the header <string> is included,
• include paths are set correctly, as I can use std::string,
• the compiler flag -std=c++0x -std=c++11 is set too.

Is stoi() missing in gcc, or is it somehow my fault?

I am using gcc (Debian 4.7.2-4) 4.7.2.

回答1:

You're using GCC 4.7.2, so std::stoi is supported. You can ignore the Eclipse warning. It should compile and run fine. The problem is with the Eclipse editor, not with GCC.

(You only need the -std=c++11 or -std=gnu++11 [to also get the GCC extensions] flag, btw. -std=c++0x is just a deprecated synonym.)

回答2:

You can get rid of the red squiggles in eclipse, (from here):

Project Properties->C/C++ General->Preprocessor Include Paths, Macros->[Providers] tab->your Built-in Compiler Settings provider (toolchain dependent). Click on "Workspace Settings" link which gets you to "Settings" property page, select [Discovery] tab and your provider again. There is "Command to get compiler specs", add "-std=c++11" in there.

hit apply and close everything, then index->rebuild and you should be all set.

Or, if your version of eclipse is older, you might just have to do this:

Project->Properties->C/C++ Build->Discovery Options->GCC C++ Compiler

and add the "-std=c++11" flag to the invocation arguments there. This is "deprecated" though, so you may want to consider updating Eclipse since you're updating your compiler too.