Void Function Problem help

[Default99]

I've got a problem with the bubble sort function:

void bubble_sort(long [],long);


int main()
{
  long array[100], n, c, d, swap;


  printf("Enter number of elements\n");
  scanf("%ld", &n);


  printf("Enter %ld integers\n", n);


  for (c = 0; c < n; c++)
    scanf("%ld", &array[c]);


  bubble_sort(array, n);


  printf("Sorted list :\n");


  for ( c = 0 ; c < n ; c++ )
     printf("%ld\n", array[c]);


  return 0;
}


void bubble_sort(long list[], long n)
{
  long c, d, t;


  for (c = 0 ; c < ( n - 1 ); c++)
  {
    for (d = 0 ; d < n - c - 1; d++)
    {
      if (list[d] > list[d+1])
      {


        t         = list[d];
        list[d]   = list[d+1];
        list[d+1] = t;
      }
    }
  }
}

The problem is , if i delete the "void bubble_sort(long [],long);" line ,it shows up the "conflicting types for bubble_sort" and "implicit declaration of function bubble_sort" warnings .Can anyone explain why that line is necessary?(By the way i'm REALLY new to c so go easy on me...)

[GReaper]

This happens because if the compiler doesn't know what the function prototype is, in C specifically, it creates an implicit prototype of the form:

int functionName();

which later comes into conflict with your definition of the same function.

Implicit declaration is an old rule and actually was declared invalid in C99, but many compilers still support it...

[laserlight]

The problem is , if i delete the "void bubble_sort(long [],long);" line ,it shows up the "conflicting types for bubble_sort" and "implicit declaration of function bubble_sort" warnings .Can anyone explain why that line is necessary?(By the way i'm REALLY new to c so go easy on me...)

At the point where you call the bubble_sort function in the main function, the bubble_sort function needs to be declared. This can be done by defining (implementing) the bubble_sort function before the main function, but instead of doing that, you can forward declare the bubble_sort function (e.g., what you did with that line) before the main function, then define the bubble_sort function after the main function.

If you don't do this, then at the point bubble_sort is called in the main function, the compiler may assume that the bubble_sort function has int parameters (i.e., defaulting to int), hence the "conflicting types for bubble_sort" warning message.

[userxbw]

it works perfectly fine for me just how it is posted, ( other than the two variables that are not needed at the time of posting, d, and swap) maybe you could also try to find a more updated compiler to install that is free on line and use that one instead of what you are now using.

[Matticus]

it works perfectly fine for me just how it is posted,

Their question was related to an issue when deleting an important line.

The problem is , if i delete the "void bubble_sort(long [],long);" line ,it shows up the "conflicting types for bubble_sort" and "implicit declaration of function bubble_sort" warnings .

[john.c]

userxbw can't even understand the questions. Clearly English is not his first language (or if it is, that's pathetic). However, it seems to be just pure carelessness.

[userxbw]

userxbw can't even understand the questions. Clearly English is not his first language (or if it is, that's pathetic). However, it seems to be just pure carelessness.

fart.... lets see here, he has his prototype to his function in the proper place. he has the definition in the write place. the function itself written out under main, and main, and it compiles and runs and does what it is suppose to do. without making any adjustments in my compiler. and you have a serious personalty issue that you defiantly need to look in to. Sorry your mommy didn't breast feed you enough or maybe she did. I do not know perhaps you need to look into that more too.

as far as me not reading the entire question or missing that one part in there says nothing about your personality disorder does it?

[Default99]

thanks for the anwers everybody I got it.The void function has to be before main and the warnings don't show up

[Matticus]

@userxbw and @john.c - please knock it off.

@Default99 - The way you have it is preferable, but you can also define the function before main. See post #2 here.