Command Line Arguments in C Explained
Updated on Nov 14, 2022 | 7 min read | 6.6k views
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Updated on Nov 14, 2022 | 7 min read | 6.6k views
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Command-line arguments are used when a program needs to be controlled from the outside instead of internally. It is a text interface for developers where arguments are directly passed to the primary method.
The values that are passed within a function when it is called are termed as arguments. In other words, an argument is a parameter that is passed to a given method when invoked.
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Syntax:
int main() { /* … */ }
The above code receives the command and passes it off to the computer’s operating system to run. These commands are always invoked when a code is being executed.
CC and C++ command-line arguments are pretty easy to implement because of their simplicity and easily decipherable syntaxes.
To pass command line arguments, the main function needs to be defined by two arguments:
Syntax:
int main(int argc, char *argv[]) { /* … */ }
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With the help of the command line, developers can access a range of files and folders on their computers. A given program that contains several command-line arguments may quickly identify the sources or destinations of the given data. It also has the potential to alter the functioning of the program. It makes the building process easier to put in source control.
In the field of development, a wide range of tasks doesn’t require actual visualisation. In such cases, all functions can be performed with the help of command-line arguments. There is a very rare requirement for a literal graphical interface. This helps save a lot of finances, effort, and resources.
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Command-line arguments have quite a few interesting and useful properties. They are as follows:
Following is a demo program for command line arguments in C:
// C program to illustrate
// command line arguments
#include<stdio.h>
int main(int argc,char* argv[])
{
int counter;
printf(“Program Name Is: %s”,argv[0]);
if(argc==1)
printf(“\nNo Extra Command Line Argument Passed Other Than Program Name”);
if(argc>=2)
{
printf(“\nNumber Of Arguments Passed: %d”,argc);
printf(“\n—-Following Are The Command Line Arguments Passed—-“);
for(counter=0;counter<argc;counter++)
printf(“\nargv[%d]: %s”,counter,argv[counter]);
}
return 0;
}
The output differs according to various scenarios. They have been further explained individually.
To produce the following output, the code has to be executed without passing an argument:
Output 1 –
$ ./a.out
Program name is: ./a.out
No Extra Command Line Argument Passed Other Than Program Name
To produce the following output, the code has to be executed with three arguments.
Output 2 –
$ ./a.out First Second Third
Program name is: ./a.out
Number of Arguments Passed: 4
—-Following Are The Command Line Arguments Passed—-
argv[0]: ./a.out
argv[1]: First
argv[2]: Second
argv[3]: Third
The code needs to be compiled and executed with a single argument that has to be separated by space while being inside quotes to produce the following output.
Output 3 –
$ ./a.out “First Second Third.”
Program name is: ./a.out
Number of Arguments Passed: 2
—-Following Are The Command Line Arguments Passed—-
argv[0]: ./a.out
argv[1]: First Second Third
The code must be compiled and executed with a single argument separated by space but within single quotes to produce the following output.
Output 4 –
$ ./a.out ‘First Second Third’
Program name is: ./a.out
Number of Arguments Passed: 2
—-Following Are The Command Line Arguments Passed—-
argv[0]: ./a.out
argv[1]: First Second Third
There are several benefits of using command line arguments in C. They are as follows:
Talking of advantages in various command-line arguments, the following is another detailed example or demonstration of how you should implement them.
#include <stdio.h>
#include <conio.h>
//main method is called to which the command line arguments are passed to the program
int main(int argc, char *argv[])
{
//an integer variable is defined
int a;
//if the condition is applied to check if the count of arguments passed to the program is greater than or equal to two, and if the condition is true, the command line arguments passed to the program are printed. Otherwise, no argument is passed to the program is printed
if(argc >= 2)
{
printf(“The arguments passed to the program are:\n”);
for(a = 1; a < argc; a++)
{
printf(“The argument passed to the program is: %s\t”, argv[a]);
}
}
else
{
printf(“No argument is passed to the program\n”);
}
return 0;
}
Output:
No argument is passed to the program.
The command-line arguments are passed to the program in the code mentioned above by calling the main method. The next step is the definition of an integer variable. Next, the condition is passed to check if the count of arguments passed to the program is greater or equal to 2. The command-line arguments passed to the program are printed if the condition is true. If not, no argument is passed to the program and printed.
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