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#include <stdio.h>
void swap1(int *a, int *b);
void swap2(int *a, int *b);
void swap3(int *a, int *b);
int main()
{
int a = 2;
int b = 6;
printf("Before swap, a = %d, b = %d\n", a, b);
swap1(&a, &b);
printf("First swap, a = %d, b = %d\n", a, b);
swap2(&a, &b);
printf("Second swap, a = %d, b = %d\n", a, b);
swap3(&a, &b);
printf("Third swap, a = %d, b = %d\n", a, b);
return 0;
}
void swap1(int *a, int *b)
{
*a = *a ^ *b;
*b = *a ^ *b; //*b = *a ^ *b = (*a ^ *b) ^*b = *a ^ (*b ^ *b) = *a ^ 0 = *a;
*a = *a ^ *b; //*a = *a ^ *b = (*a ^ *b) ^*a = (*a ^ *a) ^*b = 0 ^ *b = *b;
}
void swap2(int *a, int *b)
{
*a = *a + *b;
*b = *a - *b;
*a = *a - *b;
}
void swap3(int *a, int *b)
{
*a = *a + *b - (*b = *a); //*b=*a是一个复试表达式,它除了将*a赋给*b外,它本身可以当作一个数,这个数的值就是*a.
}
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