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This is a discussion on codes within the C Programming forums, part of the General Programming Boards category; Before you work on reversing the loop, check that you have the first one, really correct: 1) Did you add ...

  1. #31
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    Before you work on reversing the loop, check that you have the first one, really correct:

    1) Did you add the end of string char onto the end of the string, yet? (as mentioned by iMalc). That should go right after the for loop finishes.

    2) Did you check out Laserlight's concern about the i++ when there is an empty space? Your code should fail if there are two spaces in a row. (and is it necessary to increment the i when you reach a space? Why not let the loop handle incrementing the i?).

    Reversing the loop would mean starting from the end, and decrementing the loop counter (i-- instead of i++), if you want to use a similar logic.

    We have no idea what is done "deliberately" and what is not. You can see hundreds of examples of how to post right, and how to format your code correctly here. Follow them, and please - forget being "thin skinned", here. Think of "water off a duck's back", as much as you can. The best excuse here, is no excuse at all. Like Nike says: "Just do it". You'll learn far more than you will in an argument -- unless it's an argument about code, of course!

  2. #32
    Master Apprentice phantomotap's Avatar
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    and about the code, why on earth are you so aggressive?? it's not like i did it Deliberately.. so don't threat.
    O_o

    Do you really think "Post reasonable code or I will not continue to help." is a threat? That greatly reduces the meaning of the word "threat".

    *shrug*

    Anyway, it works like this; the people don't want to waste their time helping someone who continually posts code that is difficult to reason about. We can't help with code we can't reason about.

    This isn't about threats. It is about you giving people the perception that you are wasting their time.

    Soma

  3. #33
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    Quote Originally Posted by iMalc View Post
    That code you've posted fails to nul-terminate the string afterwards. It will work provided that there are nuls in the rest of the buffer, but this code should not rely on that.
    The only problem I can see with that code is the case were a space is before the null character:
    Code:
    #include <stdio.h>
     
    int main(void)
    {
        char string[] = "a b c \0xxxx";
        int i;
    
        printf(">%s<\n", string);
    
        for (i = 0; string[i] != '\0'; i++)
        {
            printf("%d - %c\n", i, string[i]);
            if (string[i] == ' ')
            {
                string[i] = string[i + 1];
                string[i + 1] = ' '; 
                i++;
                printf("%d - %c\n", i, string[i]);
            }
        }
    
        printf("\n>%s<\n", string);
        return 0;
    }
    Then i will be out of bounds.
    But according to the assignment in post #1 the input has to be cleaned (removing leading and trailing spaces and redundant spaces in between). Thus adding
    Code:
    string = clean_input(string);
    at the beginning of the function makes it save.

    Bye, Andreas

  4. #34
    Algorithm Dissector iMalc's Avatar
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    Quote Originally Posted by CproG100 View Post
    how can i reverse the loop ? i'm just a begginer so this things are new to me.
    and about the code, why on earth are you so aggressive?? it's not like i did it Deliberately.. so don't threat.
    To reverse the loop, think about where is starts and where it ends. Then instead of going from a to b, it will need to go from b to a. If it went up each time before, then now it will go down each time. Sorry, I'm trying to do this through hinting.

    Not trying to be aggressive there. Call it shock treatment, though a mild version at that. We simply want you to realise the importance of it, and make things easy on everyone. You'd be surprised how often beginners cant find a bug purely because of poor code formatting. They're shooting themselves in the foot; Don't be one of them.

    True yeah there is only a problem when the function ends with a space, but it's so much easier to fix that than wasting time tracking down the problem later because you introduced a bug elsewhere that stopped the space being trimmed off, or it was used from somewhere where spaces were not trimmed.
    Last edited by iMalc; 09-05-2012 at 01:37 PM.
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