Thread: Zed Shaw Learn C The Hard Way - Extra Credit 14.3 questions 2 and 3.

Hi
Just needed to post a couple of exercises im struggling on from Learn C the Hard Way - exercise 13: Exercise 13: Switch Statement
The "extra credit" Im not sure about is:

• Use the ',' (comma) to initialise letter in the for-loop. &
• Make it handle all of the arguments you pass it with yet another for-loop.

The code I've come up with is below I hope its readable....
I can understand how to make it handle a second argument but not an indefinite amount. I also can't understand how to initialise Letter in the for-loop using comma.

If theres somebody who doesnt mind explaining this to me I would very much appreciate it.

Thanks very much

Code:

#include <stdio.h>
int main(int argc, char *argv[])
 {
    if(argc < 2) {
        printf("ERROR: You need one argument.\n"); // this is how you abort a program
        return 1;
    }


    int i = 0;
    for(i = 0; argv[1][i] != '\0'; i++) {
        char letter = argv[1][i];


    switch(letter) {
        case 'a':
        case 'A':
            printf("%d: 'A'\n", i);
             break;
        case 'e':
        case 'E':
            printf("%d: 'E'\n", i);
            break;
        case 'i': 
        case 'I':
        printf("%d: 'I'\n", i); 
        break;


        case 'o':
        case 'O':
            printf("%d: 'O'\n", i);
             break;
        case 'u': 
        case 'U':
            printf("%d: 'U'\n", i);
            break;
        case 'y':    
        case 'Y':
            if(i > 2) {
                // it's only sometimes Y
                 printf("%d: 'Y'\n", i);
            }
            break;


        default:
            printf("%d: %c is not a vowel\n", i, letter);
        }
    }
    if(argc >= 2) {    
        for(i = 0; argv[2][i] != '\0'; i++) {
            char letter = argv[2][i];


        switch(letter) {
            case 'a':
            case 'A':
                printf("%d: 'A'\n", i);
                 break;
            case 'e':
            case 'E':
                printf("%d: 'E'\n", i);
                break;
            case 'i': 
            case 'I':
                printf("%d: 'I'\n", i); 
            break;


            case 'o':
            case 'O':
                printf("%d: 'O'\n", i);
                 break;
            case 'u': 
            case 'U':
                printf("%d: 'U'\n", i);
                break;
            case 'y':    
            case 'Y':
                if(i > 2) {
                    // it's only sometimes Y
                     printf("%d: 'Y'\n", i);
                }
                break;


            default:
                printf("%d: %c is not a vowel\n", i, letter);
            }
        }
    }    


    
    return 0; 
}

Originally Posted by Smjert

The first requirement is just telling you to change one line, from what i understand (even though i fail to see the reason):

Code:

char letter = ',';

I suggest you both google on the for loop, or get a good book which will tell you how to use a comma within the for statement.

A comma allows you to specify multiple statements, and can be used just about anywhere, including in this case as one of the parameters of a for loop.

Code:

int i, j, k;
/* ... */
    i = 1, j = 2, k = 3;

Originally Posted by gemera

I suggest you both google on the for loop, or get a good book which will tell you how to use a comma within the for statement.

I think it was only a language problem, i very well know about the comma in the for statement but when i read that in, i though about letter character that was already inside the body of the for loop.
So basicly i read that as "initialize letter with the comma character". :P.