function return problem

This is a discussion on function return problem within the C Programming forums, part of the General Programming Boards category; Code: #include <stdio.h> #include <string.h> char* reverse(char* a) { int temp, x, y = strlen(a) - 1; for ( x ...

  1. #1
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    function return problem

    Code:
    #include <stdio.h>
    #include <string.h>
    
    char* reverse(char* a)
    {
      int temp, x, y = strlen(a) - 1;
    
      for ( x = 0; x < y; x++, y-- )
        temp = a[x], a[x] = a[y], a[y] = temp;
    
      return a;
    }
    
    int main()
    {
        char *text = "hello world";
    How do I reverse variable text using reverse() and assign the result to a new variable char*? Thanks.

  2. #2
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    temp = a[x], a[x] = a[y], a[y] = temp;
    These are separate statements, need to separated by ;

  3. #3
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    When you post a program like this, it's always a good idea to state what specifically is the problem. For example, any errors messages or unexpected behavior.

    I would imagine any problems are coming from your use of compound assignment statements. Try and separate them out a bit to make them easier for you to read.

  4. #4
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    Everything works fine. You don't need to worry about function reverse(). My problem is that I don't know how to assign what reverse() returns to a new variable.

  5. #5
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    Code:
    y = f(x);
    Where y is the variable you want the return value assigned to, f is your function, and x is your parameter.

  6. #6
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    OK, but what type should y be?

  7. #7
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    Whatever type you're returning. In this case, a pointer to char (char *).

  8. #8
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    It doesn't work
    Code:
    #include <stdio.h>
    #include <string.h>
    
    char* reverse(char* a)
    {
      int temp, x, y = strlen(a) - 1;
    
      for ( x = 0; x < y; x++, y-- )
        temp = a[x], a[x] = a[y], a[y] = temp;
    
      return a;
    }
    
    int main()
    {
    	char *text = "hello world";
    	char *reversed = reverse(text);
    
    	return 0;
    }
    Try to run that.

  9. #9
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    Everything works fine
    Apparently not. Try making the changes already suggested to you. On second inspection, your return function is in serious need of a complete re-write. You take a pointer to an array as a parameter, but then treat that pointer like the array itself.

  10. #10
    & the hat of GPL slaying Thantos's Avatar
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    You are trying to modify a string literal. String literals are allowed to be placed in read only memory.

    Try changing
    Code:
    char *text
    to
    Code:
    char text[]

  11. #11
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    Worked
    Thanks!

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