How to return a value to the calling function without using return statement?

The function proto type like int xxxx(int)开发者_如何学编程 or void xxx(int)

You could use a global variable (or, a little better, you could use a static variable declared at file scope), or you could change your functions to take an output parameter, but ultimately you should just use a return statement, since that's really what it's for.

The two standard ways to return values out of functions in C are to either do it explicitly with the return statement, or to use a pointer parameter and assign into the object at the pointer.

There are other ways, but I'm not going into them for fear of increasing the amount of evil code in the world. You should use one of those two.

Use pass by reference:

void foo(int* x, int* y) {
 int temp;
 temp = *x;
 x* = *y;
 y* = temp;
}

void main(void) {
 int x = 2, y=4;
 foo(&x, &y);
 printf("Swapped Nums: %d , %d",x,y);
}

1. You could have a global variable that you assign the value to.
2. You could pass an object that stores the integer, and if you change it in the function, it'll change elsewhere too, since objects are not value type.

It also depends on the programming language that you're using.

EDIT: Sorry I didn't see the C tag, so ignore my last statement

Typically you provide a reference to an external variable to your function.

void foo(int *value)
{
   *value = 123;
}

int main(void)
{
  int my_return_value = 0;
  foo(&my_return_value);
  printf("Value returned from foo is %d", my_return_value);
  return 0;
}

The simple answer is given a prototype like the first one you must use the return statement as the int return value dictates it.

In principle it is possible to do something horrible like cast a pointer to an int and pass it in as a parameter, cast it back and modify it. As others have alluded to you must be sure you understand all the implications of doing this, and judging by your question I'd say you don't.

int wel();
int main()
{
int x;
x = wel();
printf("%d\n",x);
return 0;
}
int wel()
{
register int tvr asm ("ax");
tvr = 77;
}

Compiled with GCC compiler in ubuntu machine. In borland compiler, different way to return.

If you need to return more than one value, why not use a pointer to a new allocated struct?

typedef struct { int a, char b } mystruct;
mystruct * foo()
{
    mystruct * s = (mystruct *) malloc(sizeof(mystruct));
    return s;
}

Not tested, but should be valid.