question about returning an array

This is a discussion on question about returning an array within the C++ Programming forums, part of the General Programming Boards category; i would like to write a function to return a array.... should i write in this way? Code: char get_local_ftp_Sdir() ...

  1. #1
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    question about returning an array

    i would like to write a function to return a array....
    should i write in this way?

    Code:
    char get_local_ftp_Sdir()
    	{
    		char local_ftp_Sdir[256] = "webRfq\\ftp";
    		return *local_ftp_Sdir;
    	}

    if it is correct, would you please explain what does it mean by
    return *local_ftp_dir??

    thank you.

  2. #2
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    That is not correct. That would return the first character in the array. Your return type is "char" so a single character is all that can be returned. You need to either pass an array as a parameter and fill it in or return a char* like so

    Code:
    #include <iostream>
    using namespace std;
    
    char* Print( void )
    {
      static char s[] = "Hello World";
      return s;
    }
    
    int main( void )
    {
      cout << Print( ) << endl;
      return 0;
    }
    Note that you make the array static so the variable is placed on the heap and not on the stack. If it was on the stack it would be destroyed at the end of the function Print's scope. We are ok if it is on the heap.
    "...the results are undefined, and we all know what "undefined" means: it means it works during development, it works during testing, and it blows up in your most important customers' faces." --Scott Meyers

  3. #3
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    thank you

    thank you for teaching me ^_^

  4. #4
    Cat
    Cat is offline
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    You are much better off using either std::string (for strings) or std::vector (for arrays of any other type). In fact, it would be a good idea to replace ANY dynamically allocated array with a std::vector, and it wouldn't hurt to replace all arrays in general.

    See Return Pointer Deallocation for more discussion of this.

  5. #5
    Super Moderator VirtualAce's Avatar
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    Correct me if I'm wrong, but doesn't that return a pointer to a portion of the stack that theoretically can be overwritten later?? Since that array has not been created on the heap doesn't it reside on the local stack of the function at negative offsets to EBP? Since C does a mov esp,ebp and yet is returning a pointer to the stack portion above EBP won't this cause problems later?

    Not to stray off topic, but Just curious

  6. #6
    Just because ygfperson's Avatar
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    Originally posted by Bubba
    Correct me if I'm wrong, but doesn't that return a pointer to a portion of the stack that theoretically can be overwritten later?? Since that array has not been created on the heap doesn't it reside on the local stack of the function at negative offsets to EBP? Since C does a mov esp,ebp and yet is returning a pointer to the stack portion above EBP won't this cause problems later?

    Not to stray off topic, but Just curious
    I'm not completely sure on this, but I think there is memory for the heap, local variables, and global variables.

  7. #7
    Super Moderator VirtualAce's Avatar
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    Sorry all - did not read Mr. Wizard's post carefully enough. Sometimes I just scroll through these things too fast.



    I failed to notice that he made the array static. Doh!!!

    :konk:

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