Thread: command line parser

hello all, new semester, new problems...ahhh I love it!

anyhow, I'm supposed to write a simple command line argument parser, and for some odd reason it does not want to work. The requirments are the following:

if the command line is:

Code:

parse 123ds24

then the prog should display

Code:

123
24

if the command line is

Code:

parse 123ddd36 356m7

then

Code:

123 
36
356
7

I think you know what I mean...anyhow, below is my code...the problem arises when there is a letter in the string, it just skipps it and goes to the next argument, any suggestions?

Code:

#include <iostream>
#include <cctype>

using namespace std;

int main(int argc, char *argv[])
{
	int intVal = 0;
	char c;

	if ( argc == 1 ) {
		cout << "\nThere is nothing to parse!\n";
		cout << endl;
	} else {
		
		for ( int i = 1; i < argc; i++ ) {
			c = argv[i][i-1];
			
			if ( isalpha(c) ) continue;
			else{
				intVal =  atoi( argv[i] );
				cout << intVal << endl;
			}
		}
	}

	return 0;
}

thanks,

axon

You're going to need two loops, one which increments each time you check a char in an argument, and one which increments each time you finish checking a whole argument...to make it simple you wont even need variables, just check whether the char in argv[arg][chr] isnt a letter (with isalpha() )

Edit:

To get you started:

Code:

#include <iostream>
#include <cctype>

using namespace std;

int main(int argc, char *argv[])
{
   for (int arg=1;arg<argc;arg++)
   {
           for (int chr=0;argv[arg][chr]!='\0';chr++)
          {
             ...
          }
          ...
    }



	return 0;
}

thanks for the reply JaWiB, but I have figured it out before...this is what summer does to me...going from 30 hours of coding a week to maybe 2! ahh...but oh well time to get back into the nic of things. Anyways, below is the solution for anyone interested.

Yes I did need a double loop to go through each element of the array, and atoi(c) only displays digits unil none digit so

Code:

int x = atoi( "324dd345");

would result in x being 324 only. This is just for completeness. Yes this was just the warm up to this semester...I will visit in a day or two about a doubly linked grid world prog that has some runtime requirements...what fun!

solution:

Code:

#include <iostream>
#include <cctype>
#include <cstring>

using namespace std;

int main(int argc, char *argv[])
{
	int a=0; //counter for amount of letters
	char c;

	if ( argc == 1 ) {	//check for amount of arguments
		cout << "\nThere is nothing to parse!\n";
		cout << endl;
	} else {
		for ( int i = 1; i < argc; i++ ) {
			for ( int j = 0; j < strlen(argv[i]); j++ ){
				c = argv[i][j];	//step through each string and
				if ( isdigit(c) ) { //check if value is a digit
					if ( a > 0 ) {
						cout << endl;
						a=0;
					}
					cout << argv[i][j];// << endl;
				}else { a++; } //if value is not digit increment a
			}
			cout << endl;
		}
	}

	return 0;
}

this could be probably made much nicer, esspecially the a++ thing, but oh well...I still have some days before the due date...

axon

axon,
I suggest you to use strtok(). Read it about it here. There are also other docs which may matter to you.
http://<br /> <a href="http://www.g...html</a><br />

cheers