C ++ call-by
To thetraditional values of parameters passed to call thefunction, copy the actual values of the parameters to the formal parameters of the function. In this case, a modified form of the parameters within the function will not affect the actual parameters.
By default, C ++ using thecall-by-waysto pass parameters. Generally, this means that the code within the function does not change the actual parameters used to call the function. Functionswap () is defined as follows:
// 函数定义 void swap(int x, int y) { int temp; temp = x; /* 保存 x 的值 */ x = y; /* 把 y 赋值给 x */ y = temp; /* 把 x 赋值给 y */ return; }
Now, let us by passing actual arguments to call the functionswap ():
#include <iostream> using namespace std; // 函数声明 void swap(int x, int y); int main () { // 局部变量声明 int a = 100; int b = 200; cout << "交换前,a 的值:" << a << endl; cout << "交换前,b 的值:" << b << endl; // 调用函数来交换值 swap(a, b); cout << "交换后,a 的值:" << a << endl; cout << "交换后,b 的值:" << b << endl; return 0; }
When the above code is compiled and executed, it produces the following results:
交换前,a 的值: 100 交换前,b 的值: 200 交换后,a 的值: 100 交换后,b 的值: 200
The above example shows that, although a change in the function and the value of b, but in fact, a and b values are not changed.