Thread: Argv and strcmp help

I am trying to find a way to essentially say if argv[4] is nothing, in other words if there was not argv [4] given, then do so and so. this is what i have so far

Code:

#include<stdio.h>
#include <stdlib.h>
#include<string.h>

int main(int argc, char *argv[]){
   if ((strcmp (argv[4], "dec") == 0 )|| (strcmp (argv[4], "????????") == 0))
    printf("first times a charm\n");

return 0;
}

what do i put in for the ????? to say if there is no fourth argument do the printf


mind you i will have another if later on that states if argv[4] is anything other than dec, oct, or hex, or no argument at all print out an error

hope my jibberish is clear enough

If less then 5 arguments are passed, then argv[4] is nothing.
Less then 5 arguments are passed; therefor argv[4] is nothing.

First, check to see how many arguments were given on the command line. If this check is passed, check to see if argv[4] is a valid value. A switch statement seems like a good way to do it.

Originally Posted by laxkrzy

I am trying to find a way to essentially say if argv[4] is nothing, in other words if there was not argv [4] given, then do so and so. this is what i have so far

In the C entry procedure (main) argc tells you how many command line arguments there are... Your program can test it to see if there are 5 arguments and govern itself accordingly. (Remember argv[4] is the 5th argument)

so simply put something like:

Code:

if(len(argc)<5)
{
      printf("charming");
}

if( argc>=5 )
puts("argv[0] is valid"),
puts("argv[1] is valid"),
puts("argv[2] is valid"),
puts("argv[3] is valid"),
puts("argv[4] is valid");

Originally Posted by CommonTater

In the C entry procedure (main) argc tells you how many command line arguments there are... Your program can test it to see if there are 5 arguments and govern itself accordingly. (Remember argv[4] is the 5th argument)

Actually the argv[4] IS the 4th argument, since argv[0] is the program name ( which in fact can be an empty string, if it is not available in the current environment - (?) )

Originally Posted by kmdv

Actually the argv[4] IS the 4th argument, since argv[0] is the program name ( which in fact can be an empty string, if it is not available in the current environment - (?) )

argv[0] is the first argument and in this case the called program. this must not be NULL(at least on *nix). you need an argument to the execve system call, no?

AFAIK the argc can be 0. And I just wanted to point out that it is not really an argument (for the program), as laxkrzy might understand it this way.