There are two ways to place comments in code: //, or /*and */. The // indicates
that any characters on the rest of that line are to be treated as comments and not
acted on by the computer when the programexecutes. The /*and */ pair start and end
blocks of comment that may span multiple lines. The /*is used to start the comment,
and the */is used to indicate the end of the comment block.
Sample Program
You are now ready to review your first program. We will start by showing the program
with // comments included and will follow up with a discussion of the program.
//hello.c //customary comment of program name
#include
//needed for screen printing
main ( ) { //required main function
printf("Hello haxor"); //simply say hello
} //exit program
This is a very simple program that prints ???Hello haxor??? to the screen using the printf
function, included in the stdio.h library. Now for one that??™s a little more complex:
//meet.c
#include // needed for screen printing
greeting(char *temp1,char *temp2){ // greeting function to say hello
char name[400]; // string variable to hold the name
strcpy(name, temp2); // copy the function argument to name
printf("Hello %s %s\n", temp1, name); //print out the greeting
}
Gray Hat Hacking: The Ethical Hacker??™s Handbook
126
Chapter 6: Programming Survival Skills
127
PART III
main(int argc, char * argv[]){ //note the format for arguments
greeting(argv[1], argv[2]); //call function, pass title & name
printf("Bye %s %s\n", argv[1], argv[2]); //say "bye"
} //exit program
This program takes two command-line arguments and calls the greeting() function,
which prints ???Hello??? and the name given and a carriage return.
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