Just Dropping In

[Audacitor]

Hey Guys.  Been awhile since I've been on, so I wanted to drop in and let ya know that I haven't given up on WZ2100.  I got my programming books a few weeks ago, and I've been having a right fun time with them (multi-dimensional arrays are fun).  I'm currently working through defining functions, which is something I vaguely knew how to do going in, but there's a lot of stuff a apparently missed out on by reading web docs on C.

Which I suppose leads me to bring up a little trouble I've been having.  Is there anyway to return more than one variable?  And is there any way to return an array?  I know they're just stupid questions, and I'll probably find out for myself if I keep reading, but there is a little side project I've been working on to hone my skills, and it's stuck until I can get those out of the way.  Thanks all, and see ya later.

[DevUrandom]

All code is C99.

Code: Select all

typedef struct { int a, b; } myStruct_t;

// Of course you don't declare structs just for the fun itself
// (i.e. not just to return multiple values, without using the type in some other place)
myStruct_t myMultiReturnFunction(void)
{
  return (myStruct_t){ 2, 3 }; // Return a struct containing two integer values: 2 and 3
}

// Better in case the type you want to return is not a struct like the above:
void myMultiReturnFunction2(int *a, int *b)
{
  *a = 2; // Set memory at the provided pointers
  *b = 3;
}

If you want to return error codes in "addition", it depends on the conventions of your API.
For example you return UINT_MAX or NULL to indicate an error.

Code: Select all

// Bad practise, as long as it is not exactly clear who is to free(array);
char * myArrayReturnFunction(void)
{
  char * array = malloc(10); // Allocate a piece of memory, size: 10 bytes
  for (unsigned int i = 0; i < 10; i++)
    array[i] = i; // Initialise with 0,1,2,...
  return array; // Return pointer to memory
}


// A little bit better:
typedef struct { char a[10] } myArrayWrap_t;

myArrayWrap_t myArrayReturnFunction2(void)
{
  return (myArrayWrap_t){ {0,1,2,3,4,5,6,7,8,9} }; // Return a struct containing an array
}


// Probably prefered:
void myArrayReturnFunction3(char array[], unsigned int size)
{
  for (unsigned int i = 0; i < size; i++)
    array[i] = i; // Set memory at provided pointer, take care of the size
}
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