Command Line Arguments

Command Line Arguments

• It is a technique of providing input to c program before execution of program begins.
• While executing our program from command prompt we can pass data.
• This data which is passed form command prompt is called as command line argument.

• To receive command line argument function main has to be specially designed.
Syntax:

    main(int argc, char *argv[])
  {
    Statements
    ----------
  } 

• Where
• argc – it is an int value that contains total no of args + 1
• argv – it is an array of pointer to strings that contains programname and all args.
Note – argname may be different but their type must be specified.

argc - 5
• argv[0] - "Demo"
• argv[1] - "ram"
• argv[2] - "shyam"
• argv[3] - "gopal"
• argv[4] - "4117"

  #include<stdio.h>
  main(int argc,char *argv[])
  {
    int i;
    printf("All arguments are ");
    for(i=1;i<argc;i++)
    printf("\n%s",argv[i]);
  }

All arguments are
  

Data Conversion functions

• The command line arguments are received as string. So to convert them into different types c language provides us different functions in stdlib.h
• int atoi(char *str) – will convert string to int
• long atol(char *str) – will convert string to long int
• float atof(char *str) – will convert string to float

  #include<stdio.h>
  #include
  main(int argc,char *argv[])
  {
    int p,n;
    float r,si;
    p=atoi(argv[1]);
    r=atof(argv[2]);
    n=atoi(argv[3]);
    si=p*r*n/100;
    printf("Simple Interest is %f",si);
  }

Simple Interest 5000 10.25 3
  

  #include<stdio.h>
  main(int argc ,char *argv[])
  {
    int r;
    float a,c;
    r=atoi(argv[1]);
    a=3.14*r*r;
    c=2*3.14*r;
    printf("Area is %f \nCircumference is %f",a,c);
  }

  #include<stdio.h>
  main(int argc,char *argv[])
  {
    int n,f=1,i;
    n=atoi(argv[1]);
    for(i=1;i<=n;i++)
    f=f*i;
    printf("Factorial of %d is %d",n,f);

  }

Factorial of 5