Importing C++ Programs In Python: Book Back Questions and Answers

Computer Science : Integrating Python with MySql and C++ : Importing C++ Programs In Python

Evaluation

Part – I

Choose the best answer          (1 Marks)

1. Which of the following is not a scripting language?  

(A) JavaScript

(B) PHP

(C) Perl

(D) HTML

2. Importing C++ program in a Python program is called

(A) wrapping

(B) Downloading

(C) Interconnecting

(D) Parsing

3.The expansion of API is

(A) Application Programming Interpreter

(B) Application Programming Interface

(C) Application Performing Interface

(D) Application Programming Interlink

4.A framework for interfacing Python and C++ is

(A) Ctypes

(B) SWIG

(C) Cython

(D) Boost

5.Which of the following is a software design technique to split your code into separate parts?

(A) Object oriented Programming

(B) Modular programming

(C) Low Level Programming

(D) Procedure oriented Programming

6.The module which allows you to interface with the Windows operating system is

(A) OS module

(B) sys module

(c) csv module

(d) getopt module

7. getopt() will return an empty array if there is no error in splitting strings to

(A) argv variable

(B) opt variable

(c) args variable

(d) ifile variable

8.Identify the function call statement in the following snippet.

if __name__ =='__main__':

main(sys.argv[1:])

(A) main(sys.argv[1:])

(B) __name__

(C) __main__

(D) argv

9.Which of the following can be used for processing text, numbers, images, and scientific data?

(A) HTML

(B) C

(C) C++

(D) PYTHON

10. What does __name__ contains ?                   

(A) c++ filename

(B) main() name

(C) python filename

(D) os module name

Part - II

Answer the following questions                          (2 Marks)

1. What is the theoretical difference between Scripting language and other programming language?

Ans. (i) The theoretical difference between the two is that scripting languages do not require the compilation step and are rather interpreted.

(ii)  For example, normally, a C++ program needs to be compiled before running whereas, a scripting language like JavaScript or Python need not be compiled.

(iii) A scripting language requires an interpreter while a programming language requires a compiler. A given language can be called as a scripting or programming language depending on the environment they are put to use.

2. Differentiate compiler and interpreter.

Ans.

s. No       

Compiler

(i) Scans the entire program and translates it as a whole into machine code.

(ii) It takes large amount of time to analyze the source code but the overall execution time is comparatively faster.

(iii) Programming language like C, C++ use compilers.

Interpreter

(i) Translates program one statement at a time.

(ii) It takes less amount of time to analyze the source code but the overall execution time is slower.

(iii) Programming language like Python, Ruby use interpreters.

3. Write the expansion of                    (i) SWIG               (ii) MinGW

(i) SWIG - Simplified Wrapper Interface Generator

(ii) MINGW - Minimalist GNU for Windows

4. What is the use of modules?

Ans. (i) The use of modules to break down large programs into small manageable and organized files.

(ii) Modules provide reusability of code. Define our most used functions in a module and import it, instead of copying their definitions into different programs.

5. What is the use of cd command. Give an example.

Ans. ‘cd’ command refers to change directory and absolute path refers to the couple path.

(Eg) “cd c:\program files\open office 4\program”

Part – III

Answer the following questions       (3 Marks)

1. Differentiate PYTHON and C++

Ans.

PYTHON

(i) Python is typically an "interpreted" language

(ii) Python is a dynamic-typed language

(iii) Data type is not required while declaring variable

(iv) It can act both as scripting and general purpose language

C++

(i) C++ is typically a "compiled" language

(ii) C++ is compiled statically typed language

(iii) Data type is required while declaring variable

(iv) It is a general purpose language

2. What are the applications of scripting language?

Ans. (i) To automate certain tasks in a program

(ii) Extracting information from a data set

(iii) Less code intensive as compared to traditional programming language

(iv) can bring new functions to applications and glue complex systems together

3. What is MinGW? What is its use?

Ans. (i) MinGW refers to a set of runtime header files, used in compiling and linking the code of C, C++ and FORTRAN to be run on Windows Operating System.

(ii) MinGw-W64 (version of MinGW) is the best compiler for C++ on Windows. To compile and execute the C++ program,  need ‘g++’ for Windows. MinGW allows to compile and execute C++ program dynamically through Python program using g++.

(iii) Python program that contains the C++ coding can be executed only through minGW-w64 project’ run terminal. The run terminal open the command-line window through which Python program should be executed.

4. Identify the module ,operator, definition name for the following welcome.display()

Ans. Welcome.display()

5. What is sys.argv? What does it contain?

Ans. sys.argv is the list of command-line arguments passed to the Python program, argv contains all the items that come along via the command-line input, it's basically an array holding the command-line arguments of the program.

Part – IV

Answer the following questions       (5 Marks)

1. Write any 5 features of Python.

Ans.

(i) Python uses Automatic Garbage Collection whereas C++ does not.

(ii) C++ is a statically typed language, while Python is a dynamically typed language.

(iii) Python runs through an interpreter, while C++ is pre-compiled.

(iv) Python code tends to be 5 to 10 times shorter than that written in C++.

(v) In Python, there is no need to declare types explicitly where as it should be done in C++

(vi) In Python, a function may accept an argument of any type, and retifrn multiple values without any kind of declaration beforehand. Whereas in C++ return statement can return only one value.

2. Explain each word of the following command.

Python <filename.py> -<i> <C++ filename without cpp extension>

Python <filename.py> -i <C++ filename without cpp extension>

Python : Keyword to execute the Python program from command-line

filename.py- i : Name of the Python program to executed input mode

C++ filename without cpp extension : Name of C++ file to be compiled and executed

3. What is the purpose of sys,os,getopt module in Python. Explain

Ans. This module provides access to some variables used by the interpreter and to functions that interact strongly with the interpreter,

sys.argv :

(i) sys.argv is the list of command-line arguments passed to the Python program, argv contains all the items that come along via the command-line input, it's basically an array holding the command-line arguments of the program.

(ii) To use sys.argv, you will first have to import sys. The first argument, sys.argv[0], is always the name of the program as it was invoked, and sys.argv[l] is the first argument you pass to the program (here it is the C++ file).

OS:

(i) The OS module in Python provides a way of using operating system dependent functionality.

(ii) The functions that the OS module allows you to interface with the Windows operating system where Python is running on.

os.system():

(i) Execute the C++ compiling command (a string contains Unix, C command which also supports C++ command) in the shell (Here it is Command Window).

(ii) For Example to compile C++ program g++ compiler should be invoked. To do so the following command is used.

os.system (‘g++’ + <varaiable_namel> ‘-<mode>’ + <variable_name2>

getopt module:

(i) The getopt module of Python helps you to parse (split) command-line options and arguments.

(ii) This module provides two functions to enable command-line argument parsing.

getopt.getopt method :

(i) This method parses command-line options and parameter list. Following is the syntax for this method -

(ii) <opts>,<args>=getopt.getopt(argv, options,  [long_options])

4. Write the syntax for getopt() and explain its arguments and return values

Ans. getopt.getopt method: This method parses command-line options and parameter list. Following is the syntax for this method –

<opts>,<args>=getopt.getopt(argv, options, [long_options])

Here is the detail of the parameters -

(i) argv : This is the argument list of values to be parsed (splited). In our program the complete command will be passed as a list.

(ii) options : This is string of option letters that the Python program recognize as, for input or for output, with options (like ‘i’ or o’) that followed by a colon (:). Here colon is used to denote the mode.

(iii) long_options : This parameter is passed with a list of strings. Argument of Long options should be followed by an equal sign ('='). In our program the C++ file name will be passed as string and ‘f also will be passed along with to indicate it as the input file.

getopt() method returns value consisting of two elements. Each of these values are stored separately in two different list (arrays) opts and args. Opts contains list of splitted strings like mode, path and args contains any string if at all not splitted because of wrong path or mode, args will be an empty array if there is no error in splitting strings by getopt().

For example, The Python code which is going to execute the C++ file p4 in command line will have the getopt() method like the following one. opts, args = getopt.getopt (argv, "i:",['ifile='])

Where  opts contains : [('-i', ‘c:\\pyprg\\p4')]

-i:- : option nothing but mode should be followed by :

'c:\\pyprg\\p4' : value nothing but the absolute path of C++ file.

In our examples since the entire command line commands are parsed and no leftover argument, the second argument args will be empty []. If args is displayed using print() command it displays the output as [].

5. Write a Python program to execute the following c++ coding

#include <iostream>

using namespace std;

int main()

{ cout<<“WELCOME”; return(0);

}

The above C++ program is saved in a file welcome.cpp

Ans.

#Now select File→New in Notepad and type the Python program as main.py

# Program that compiles and executes a .cpp file

# Python main.py -i welcome

import sys, os, getopt

def main(argv):

cpp_file = "

 exe_file = "

opts, args = etopt.getopt(argv, "i:",['ifile='])

for o, a in opts:

if o in ("-i", "-ifile"):

cpp_file = a + '.cpp'

 exe_file = a + '.exe'

run(cpp_file, exe_file)

def run(cpp_file, exe_file):

print("Compiling" + cpp_file)

os.system('g++' + cpp_file + '-o' + exe_ file)

print("Running" + exe_file)

print("………………….. ")

print

os.system(exe_file)

print

if __name__ == '__main__':

main(sys.argv[1:])