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usaco-guide/content/1_Intro/Intro_RunningCpp.md
Nathan Wang 7969af20bf add onlinegdb link 
source: Anthony Wang
2020-06-08 20:09:54 -07:00

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slug title author order
/intro/running-cpp Running C++ Nathan Wang, Benjamin Qi 4

Running C++ both online and locally (currently for Mac only).

Using C++

Here's a basic C++ template you may find useful:

#include <bits/stdc++.h>

using namespace std;

int main() {
    // these two lines open the file into the standard input/output,
    // so you can just use cin/cout.
    freopen("file.in", "r", stdin); // read from file.in
    freopen("file.out", "w", stdout); // write to file.out

    // Code goes here!!

}

Running Online

  • CSAcademy
    • pretty nice (unless you get "Estimated Queue Time: ...")
  • Ideone (used this for a while ...)
    • okay with an ad blocker
    • make sure your code is not public
    • sometimes randomly erases your code when you first create it (so get in the habit of copying your code before creating it!)
  • OnlineGDB

Of course, you can't use File I/O on these websites (or do a lot of other stuff ...).

Running C++ Locally (on Mac)

Clang is the default compiler for Mac OS X, but you should use G++.

Installation

I had a lot of issues when first trying to install G++ on Mac. Please let me know if these instructions do not work!

Open terminal and run

brew install gcc

According to this if brew doesn't seem to finish for a long time then

brew install gcc --force-bottle

probably suffices.

Confirmation

You should be able to compile with g++ or maybe g++-#, where # is the version number (currently 9). Running the following command:

g++-9 --version

should display something like this:

g++-9 (Homebrew GCC 9.2.0_2) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Adding Shortcuts

Open your bash profile with a text editor such as gedit (or sublime text).

brew install gedit
gedit ~/.zshenv

You can add aliases and functions here, such as the following:

alias clr="clear"
alias ZES='source ~/.zshenv'
alias ZEO='subl ~/.zshenv'
alias IMPL='cd ~/Documents/GitHub/USACO/Implementations/'
co() {
	g++-9 -std=c++11 -O2 -Wl,-stack_size -Wl,0x10000000 -Wall -Wextra -o $1 $1.cpp
}
run() {
	co $1 && ./$1
}

Now you can easily compile and run C++ from the command line by calling run.

run [prog name]

Troubleshooting

Make sure you have installed XCode command line tools.

xcode-select --install # make sure x-code command line tools are installed
softwareupdate --list
softwareupdate -i -a # installs everything

Tools

IDEs

Text Editors

Other Useful Links