*a ^= *b, *b ^= *a, *a ^= *b;

    main()

{

         void swap();

    int x=10,y=8;    

         swap(&x,&y);

    printf("x=%d y=%d",x,y);

}

void swap(int *a, int *b)

{

   *a ^= *b,  *b ^= *a, *a ^= *b;

}  

Answer:

x=10 y=8

Explanation:

Using ^ like this is a way to swap two variables without using a temporary variable and that too in a single statement.

Inside main(), void swap(); means that swap is a function that may take any number of arguments (not no arguments) and returns nothing. So this doesn’t issue a compiler error by the call swap(&x,&y); that has two arguments.

This convention is historically due to pre-ANSI style (referred to as Kernighan and Ritchie style) style of function declaration. In that style, the swap function will be defined as follows,

void swap()

int *a, int *b

{

   *a ^= *b,  *b ^= *a, *a ^= *b;

}

where the arguments follow the (). So naturally the declaration for swap will look like, void swap() which means the swap can take any number of arguments.

Blog Author: Vijay Kumar

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