Advance-C/C2/Command-line-arguments-in-C/English
Title of script: Command Line Arguments
Author: Ashwini Patil
Keywords: Video tutorial, Command Line Arguments, main()
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| Display Slide | Hello and welcome to the spoken tutorial on Command Line Arguments. |
| Display Slide | In this tutorial, we will learn about
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System Requirements |
For this tutorial I am using
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Prerequisites |
To follow this tutorial, you should be familiar with C tutorials.
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| Show the pointer to | Let us start with our program.
I have a code file. I will open it. Filename is main-with-args.c |
| Let me explain the program. | |
| #include <stdio.h>
#include <stdlib.h> |
These are the header files.
stdio.h defines core input and output functions. stdlib.h header file defines-
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| int main(int argc, char **argv) | This is our main function.
Inside this, we have passed two arguments- int argc, char **argv |
| int main(int argc, char **argv) | “argc” refers to the number of command line arguments passed to the program.
This includes the actual name of the program. |
| argv contains actual arguments starting from index 0.
Index 0 is the name of the program. Index 1 will be the first argument passed to the program. Index 2 will be the second argument passed to the program. And so on. | |
| printf("argc is %d\n",argc); | This statement will display the total number of arguments passed to the program. |
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printf("argv is %s\n",argv[1]); |
This will display the first argument passed to the program.
1 represents the argument at index 1. |
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while(argc--) |
While condition will decrement the number of arguments. |
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printf("arguments are %s\n", *argv++); |
This statement will print all the arguments passed to the program. |
| return 0; | At the end we have return 0 statement. |
| Press Ctrl+Alt+T | Let us open the terminal by pressing Ctrl+Alt+T keys simultaneously on your keyboard. |
| Compile
Type: gcc main-with-args.c -o args |
Type: gcc space main-with-args.c -o args
Press Enter |
| Execute | Type: ./args
Press Enter. |
| Point to the output on the Terminal | You can see the output as:
Total number of arguments are 1 The first argument is (null) arguments are ./args |
| Command line arguments are given during execution.
Total number of arguments are 1 as the zeroth argument is the executable filename itself. The first argument is (null) as we have not passed any argument to the program. Arguments are only one ie. ./args | |
| Highlight:
Type: ./arg.sh Sunday Monday Tuesday
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Now let us execute again
Press the uparrow key. space type Sunday space Monday space Tuesday Press Enter |
| (change in your program also) | Now we can see the output:
Total number of arguments are 4 The first argument is Sunday Argument are ./args Sunday Monday and Tuesday . |
| Let me explain the output. | |
| Output:
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Total number of arguments are 4 as ./args, Sunday, Monday and Tuesday.
The first argument is Sunday The zeroeth argument always gives executable filename. Sunday is assigned to first argument. Monday is assigned to second argument. Tuesday is assigned to third argument.
Let us summarize. |
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Summary |
In this tutorial we learnt,
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| Assignment | As an assignment,
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Watch the video available at the link shown below
It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it |
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Spoken Tutorial Workshops |
The Spoken Tutorial Project Team
Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to contact@spoken-tutorial.org |
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Acknowledgement |
Spoken Tutorial Project is a part of the Talk to a Teacher project
It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro |
| This is Ashwini Patil from IIT Bombay signning off.
Thank you for joining. |
