Compile and Run Different Languages in Python using Subprocess
To execute different programs using Python two functions of the subprocess module are used:
1.subprocess.check_call(args, *, stdin=None, stdout=None, stderr=None, shell=False)
Parameters:
args=The command to be executed.Several commands can be passed as a string by separated by “;”.
stdin=Value of standard input stream to be passed as (os.pipe()).
stdout=Value of output obtained from standard output stream.
stderr=Value of error obtained(if any) from standard error stream.
shell=Boolean parameter.If True the commands get executed through a new shell environment.
Return Value:
The function returns the return code of the command.If the return code is zero, the function simply returns(command executed successfully) otherwise CalledProcessError is being raised.2.subprocess.check_output(args, *, stdin=None, stderr=None, shell=False, universal_newlines=False)
Parameters:
args=The command to be executed. Several commands can be passed as a string by separated by “;”.
stdin=Value of standard input stream to be passed as pipe(os.pipe()).
stdout=Value of output obtained from standard output stream.
stderr=Value of error obtained(if any) from standard error stream.
shell=boolean parameter.If True the commands get executed through a new shell environment.
universal_newlines=Boolean parameter.If true files containing stdout and stderr are opened in universal newline mode.
Return Value:
The function returns the return code of the command.If the return code is zero, the function simply returns the output as a byte string(command executed successfully) otherwise CalledProcessError is being raised.
Example: Let us consider the following code example in different languages.
C++
#include <iostream> using namespace std; int main() { int a, b; cin >> a >> b; cout << "Hello World from C++.Values are:" << a << " " << b; return 0; } |
C
#include<stdio.h> int main() { printf("Hello World from C"); return 0; } |
Java
class HelloWorld { public static void main(String args[]) { System.out.print("Hello World from Java."); } } |
Hello World from C++.Values are:0 4196176
Python Code to Execute the Above Programs
In this code there are three functions created separate each for executing C,C++ and JAVA program respectively. ‘executeC()’ is used to execute the C program file.‘executeCpp()’ is used to execute the C++ program file.‘executeJava()’ is used to execute the JAVA program file.
In each method It employs the ‘subprocess.check_call’ method to execute the necessary compilation and execution commands. After execution, it prints the return code, which can indicate whether the program ran successfully.
Python3
# Python 3 program to demonstrate subprocess import subprocess import os def excuteC(): # store the return code of the c program(return 0) # and display the output s = subprocess.check_call("gcc HelloWorld.c -o out1;./out1", shell=True) print(", return code", s) def executeCpp(): # create a pipe to a child process data, temp = os.pipe() # write to STDIN as a byte object(convert string # to bytes with encoding utf8) os.write(temp, bytes("5 10\n", "utf-8")) os.close(temp) # store output of the program as a byte string in s s = subprocess.check_output( "g++ HelloWorld.cpp -o out2;./out2", stdin=data, shell=True) # decode s to a normal string print(s.decode("utf-8")) def executeJava(): # store the output of # the java program s = subprocess.check_output( "javac HelloWorld.java;java HelloWorld", shell=True) print(s.decode("utf-8")) # Driver function if __name__ == "__main__": excuteC() executeCpp() executeJava() |
Output
Hello World from C, return code 0
Hello World from C++. Values are:5 10
Hello World from Java.
Python subprocess module
The subprocess module present in Python(both 2.x and 3.x) is used to run new applications or programs through Python code by creating new processes. It also helps to obtain the input/output/error pipes as well as the exit codes of various commands. In this tutorial, we’ll delve into how to effectively use subprocessing modules to execute external functions from your Python code, pass data to them, and get results Whether you’re a beginner or an experienced Python user developer, this guide will prove useful with your skills and abilities.