how to enable c++11 in linux

Question

I wanted to use the unordered_map STL in c++, but as soon as I use the header, it gives me this error:

This file requires support for the compiler and library support for the ISO C++11 standard. This support is currently experimental and must be enabled with -std=c++11 or -std=gnu++11 compiler options.

I am attaching my code that I wanted to run, below. (Any inputs on the code are welcome too. thanks)

#include <iostream>
#include <unordered_map>
using namespace std;

class Node
{
public:
string a,b;
Node()
{
    a="hello";
    b="world";
}
};


int main ()
{
    unordered_map<Node> mymap;
    Node mynode;
    mymap.insert(mynode);
    std::cout << "myrecipe contains:" << std::endl;
  for (auto& x: mymap)
    std::cout << x.a << ": " << x.b << std::endl;

}

Edit: I got it to work by using the following commmand: g++ -std=c++11 [filename].cpp

Thanks for the help.

"This support is currently experimental and must be enabled with -std=c++11 or -std=gnu++11 compiler options." What about that is not clear to you? Note that this is _compiler_ specific, and doesn't really have anything to do with your OS (presumably you're using gcc, which is also available on windows and OSX and a couple of other platforms IIRC). — Cubic, Nov 16 '14 at 05:21
The question is how to get my code to compile without this error? thanks in advance. — pyroscepter, Nov 16 '14 at 05:28
The error message contains the relevant instructions - just add one of the options (`-std=c++11` or `-std=gnu++11`) when compiling. — Cubic, Nov 16 '14 at 05:47
[refer](https://stackoverflow.com/questions/17378969/how-to-change-gcc-compiler-to-c11-on-ubuntu) — pradeexsu, Oct 15 '20 at 12:48

score 8 · Accepted Answer · answered Nov 16 '14 at 05:22

8

The main answer to your question: specify -std=c++11 in your compile command.

Precisely which C++11 features are available will depend on your version of GCC. Here are two links that might help:

answered Nov 16 '14 at 05:22

FoggyDay

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`g++ -g -Wall -pedantic -std=c++11 -o myprog myprog.cpp`, for example. – FoggyDay Nov 16 '14 at 06:04

Arnab Nandy · Answer 2 · 2014-11-16T05:47:07.220

3

First Option:

You can remove to error with -std=c++11 in compile time.

g++ -o binary yourFile.cpp -std=c++11

Second Option to integrate the development with c++11:

You can use a makefile with the CXXFLAGS set with -std=c++11 A makefile is a simple text file with instructions about how to compile your program. Create a new file named Makefile (with a capital M). To automatically compile your code just type the make command in a terminal. You may have to install make.

Here is the code :

CXX=clang++
CXXFLAGS=-g -std=c++11 -Wall -pedantic
BIN=prog

SRC=$(wildcard *.cpp)
OBJ=$(SRC:%.cpp=%.o)

all: $(OBJ)
    $(CXX) -o $(BIN) $^

%.o: %.c
    $(CXX) $@ -c $<

clean:
    rm -f *.o
    rm $(BIN)

It assumes that all the .cpp files are in the same directory as the makefile. But you can easily tweak your makefile to support a src, include and build directories.

edited Nov 16 '14 at 05:47

answered Nov 16 '14 at 05:18

Arnab Nandy

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I tried this. it says "*** missing separator. Stop." when I type make in the terminal. please help. – pyroscepter Nov 16 '14 at 05:26
1

Make sure you're using tabs for indentation, and not just a few spaces. Makefiles seem to be picky about that. – Malcolm Crum Nov 16 '14 at 05:31
it now says clang++ command not found. any idea how to resolve that? – pyroscepter Nov 16 '14 at 05:37
Check [here](http://askubuntu.com/questions/509218/how-to-install-clang) for the resolving the error you getting, @Siddharth'elMásGrande' – Arnab Nandy Nov 16 '14 at 05:40

score 0 · Answer 3 · answered Nov 16 '14 at 05:44

0

compile with:

g++ -o binary source.cpp -std=c++11

answered Nov 16 '14 at 05:44

Rupesh Yadav.

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how to enable c++11 in linux

3 Answers3