Thread: reverse a string without string.h library

  1. #1
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    reverse a string without string.h library

    can anyone help me with my exercise.. i want to inverse a string but without using any of string.h' s library functions

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    What have you tried so far? This isn't a homework service. The basic answer is that you have to treat a string for what it is, a char array, and then iterate through the array in reverse.
    Quote Originally Posted by anduril462 View Post
    Now, please, for the love of all things good and holy, think about what you're doing! Don't just run around willy-nilly, coding like a drunk two-year-old....
    Quote Originally Posted by quzah View Post
    ..... Just don't be surprised when I say you aren't using standard C anymore, and as such,are off in your own little universe that I will completely disregard.
    Warning: Some or all of my posted code may be non-standard and as such should not be used and in no case looked at.

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    well i have tried this so far..


    Code:
    void reverse(char str[])
    {
    int i=0, j=0;
    
    printf("Enter String (up to 50 chars): ");
    scanf("%s", str);
    
    
    while(str[j] != '\0')
    {
    
    j++;
    //j--;
    
    }
    
    while(i<=j)
    {
    
    char t = str[i];
    
    str[i++] = str[j];
    str[j--] = t;
    
    }
    
    printf("%s", str);
    
    return;
    }

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    Your attempt doesn't make sense. Ask for and then get the string in main. Then pass that to your reverse function. This is a pretty basic question, search this board for "surname swap", we had a good discussion of it there. Note that since the NULL char evaluates to false for C, you can use that for string length. Additionally, there are methods of getting user input that will return the number of characters read in.
    Quote Originally Posted by anduril462 View Post
    Now, please, for the love of all things good and holy, think about what you're doing! Don't just run around willy-nilly, coding like a drunk two-year-old....
    Quote Originally Posted by quzah View Post
    ..... Just don't be surprised when I say you aren't using standard C anymore, and as such,are off in your own little universe that I will completely disregard.
    Warning: Some or all of my posted code may be non-standard and as such should not be used and in no case looked at.

  5. #5
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    Thanks a lot! Well i have managed to build this part until now but i have to figure a way to count the length of the string without using string.h

  6. #6
    ATH0 quzah's Avatar
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    Hope is the first step on the road to disappointment.

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    Quote Originally Posted by antros48 View Post
    Thanks a lot! Well i have managed to build this part until now but i have to figure a way to count the length of the string without using string.h
    Length counting is easy --and provides a real good hint on the rest of the problem as well...

    Code:
    int GetLength(char *str)
      { int i = 0;
        while ( str[ i++ ] );
        return i - 1; }

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