Having problems using STL functions_ of C++14 or C++17?

Wrote a piece of code in C++ and encountered that STL functions are not supported by the default clang compiler on Mac?
For example, this piece of code:

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n=gcd(2,3);
    cout<<n;
    return 0;
}

Compiling the code with gnu or clang compilers and getting this error?

@User-MacBook-Air % clang++ test.cpp
test.cpp:5:11: error: use of undeclared identifier 'gcd'
    int n=gcd(2,3);
          ^
1 error generated.

So what happened here?

Let's check our c++ version.

When you run clang --version, you will get something like this and would be pretty confused even if your clang/gnu is up-to-date but you still can't figure out your c++ version:

   Apple clang version 12.0.5 (clang-1205.0.22.9)
   Target: arm64-apple-darwin20.4.0
   Thread model: posix
   InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

This happens because

The gcd() function is a STL function from c++14 and above.

But by default, Clang builds C++ code according to the C++98 standard, with many C++11 features accepted as extensions.

What to do?

After going through many websites and resources, I was finally able to compile the correct methods to use c++17 on mac.
So in order to use STL functions of c++17 or c++14 or upper versions, you need to specify the version of C++ to be used which goes like this:

 -std=c++{version} {filename}.cpp

appending the c++ version to -std option.

Example:

• For clang compilers:
  

  
   clang++ --std=c++17 {filename}.cpp
  
  

• For gnu compilers:
  

  
   g++ --std=gnu++17 {filename}.cpp
  
  

• My Personal choice:
  

  
   c++ --std=gnu++17 {filename}.cpp
  
  

And that's it, you're done!

Also free feel to share other ways in the comments!!!