C programming using gcc compiler

This is a discussion on C programming using gcc compiler within the C Programming forums, part of the General Programming Boards category; Dear all, I am trying to do a program using gcc compiler to reverse a string input. I am stuck ...

  1. #1
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    C programming using gcc compiler

    Dear all,

    I am trying to do a program using gcc compiler to reverse a string input.

    I am stuck at the for loop which I think there is some mistake there. I only manage to reverse two of the letters only.

    Kindly advise.

    Below is part of my code:

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    #define size 128
    
    int main(void)
    {
        char line[size];
        printf("Enter line:");
       fgets(line, size, stdin);
    
        int n, i;
        n = strlen(line);
        
       for (i = 0; i > n; ++i)
        {
            line[i] = line[n-1-i];
         }
    
        printf("Your reverse line is %s\n, line);
    
    
       exit(0);
    
     }


    Would really appreciate someone to point out where I have gone wrong.

    Thanks.

  2. #2
    Been here, done that.
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    Run through your program by hand to see what the loop is doing. It's really obvious if you simply desk-check you program.
    Definition: Politics -- Latin, from
    poly meaning many and
    tics meaning blood sucking parasites
    -- Tom Smothers

  3. #3
    TEIAM - problem solved
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    Code:
    for (i = 0; i > n; ++i)
    The for loop executes while this condition is true. It is never true.
    Fact - Beethoven wrote his first symphony in C

  4. #4
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    Somehow i got what you meant already.

    Code:
    for (i = 0; i < n; ++i)
    Only then the condition will be true.

    For the for loop, i should use a separate count to differentiate between the length of the string and count. So that it won't affect the for loop condition.
    and i should not do my code this way.

    Code:
    line[i] = line[n-1-i]
    If my i = 0, i will end up having my array grabbing null into the array
    which i am suppose to grab my character instead.

    So far, am I right to say this way??

  5. #5
    Been here, done that.
    Join Date
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    What happened when you did the desk check?
    Definition: Politics -- Latin, from
    poly meaning many and
    tics meaning blood sucking parasites
    -- Tom Smothers

  6. #6
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    The first time i run,
    Code:
    Enter your line:testy
    your reverse is: 
    ytty
    Application Exited.

  7. #7
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    second try..

    i got it already.

    Code:
    Build Success
    ------------------------------
    Enter your line:testytesty
    your reverse is: ytsetytset
    Application Exited.

  8. #8
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    thanks guys..

  9. #9
    TEIAM - problem solved
    Join Date
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    Think about if you enter "test", what are you doing step by step?

    This looks like what you are doing with your algorithm
    Code:
    (Pseudo-ish)
    A[] = {t, e, s, t, \0}
    
    A[0] = A[3] >>> A = {t, e, s, t, \0}
    A[1] = A[2] >>> A = {t, s, s, t, \0}
    A[2] = A[1] >>> A = {t, s, s, t, \0}
    A[3] = A[0] >>> A = {t, s, s, t, \0}
    i.e. You are writing over data that you need.

    [edit]
    You seem to have solved the problem whilst I was typing!
    Good stuff.
    [/edit]
    Last edited by Click_here; 09-13-2012 at 09:59 PM.
    Fact - Beethoven wrote his first symphony in C

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