C – Command Line Arguments

Accepting Command Line arguments:

• Every C application runs by Computer Operating System.
• OS runs the program from its environment.
• Every OS consists CUI and GUI mode.
• To read command line arguments, we need to run the C program from CUI OS mode.

Run application from Command prompt:

• Cmd Prompt is Ms-DOS
• It is Command User Interface.
• OS takes command as input and open specified application which is present in that machine.
• We compile and run the code from command line using tcc compiler as follows

Code program:

#include<stdio.h> int main() {             printf(“Hello…\n”);             return 0; }

Note: save into “turboc” folder with name Program.c

Open command prompt:

Compilation:             C:/turboc> tcc Program.c                         -> Generate Program.exe file   Execution:             C:/turboc>Program.exe                         -> Generate output.

main() prototype: Regular main() function prototype is slightly different from the main() function taking command line arguments. We must define main() function as follows

int  main(int argc ,  char*  argv[ ])

where:

• ‘argc’ = argument count ( Number of arguments passed including file name)
• ‘argv’ = argument vector(list)  (List of arguments  – default type is String)

Why argument type is String by default?

• In any programming language, only String type can hold any data.
  • main(int[]) –> can take only integers
  • main(float[]) –> can take only float values.
  • main(char* []) –> can hold any type of data.
    • char* a = “10”;
    • char* b = “23.45”;
    • char* c = “g”;
    • char* d = “CBook”;