[c++] How do I compile C++ with Clang?

I have installed Clang by using apt-get in Ubuntu, and I can successfully compile C files using it. However, I have no idea how to compile C++ through it. What do I need to do to compile C++?

I do not know why there is no answer directly addressing the problem. When you want to compile C++ program, it is best to use clang++. For example, the following works for me:

clang++ -Wall -std=c++11 test.cc -o test

If compiled correctly, it will produce the executable file test, and you can run the file by using ./test.

Or you can just use clang++ test.cc to compile the program. It will produce a default executable file named a.out. Use ./a.out to run the file.

The whole process is a lot like g++ if you are familiar with g++. See this post to check which warnings are included with -Wall option. This page shows a list of diagnostic flags supported by Clang.

A note on using clang -x c++: Kim Gräsman says that you can also use clang -x c++ to compile cpp programs, but that may not be true. For example, I am having a simple program below:

#include <iostream>
#include <vector>

int main() {
    /* std::vector<int> v = {1, 2, 3, 4, 5}; */
    std::vector<int> v(10, 5);
    int sum = 0;
    for (int i = 0; i < v.size(); i++){
        sum += v[i]*2;
    }
    std::cout << "sum is " << sum << std::endl;
    return 0;
}                                                      

clang++ test.cc -o test will compile successfully, but clang -x c++ will not, showing a lot undefined references errors. So I guess they are not exactly equivalent. It is best to use clang++ instead of clang -x c++ when compiling c++ programs to avoid extra troubles.

• clang version: 11.0.0
• Platform: Ubuntu 16.04

Open a Terminal window and navigate to your project directory. Run these sets of commands, depending on which compiler you have installed:

To compile multiple C++ files using clang++:

$ clang++ *.cpp 
$ ./a.out 

To compile multiple C++ files using g++:

$ g++ -c *.cpp 
$ g++ -o temp.exe *.o
$ ./temp.exe

Also, for posterity -- Clang (like GCC) accepts the -x switch to set the language of the input files, for example,

$ clang -x c++ some_random_file.txt

This mailing list thread explains the difference between clang and clang++ well: Difference between clang and clang++

Solution 1:

  clang++ your.cpp

Solution 2:

  clang your.cpp -lstdc++

Solution 3:

   clang -x c++ your.cpp

I've had a similar problem when building Clang from source (but not with sudo apt-get install. This might depend on the version of Ubuntu which you're running).

It might be worth checking if clang++ can find the correct locations of your C++ libraries:

Compare the results of g++ -v <filename.cpp> and clang++ -v <filename.cpp>, under "#include < ... > search starts here:".