实验１　C++函数

一．实验目的：

1. 掌握定义函数的方法、函数实参与形参的对应关系以及“值传递”的方式。
2. 熟悉函数的嵌套调用和递归调用的方法。
3. 熟悉全局变量、局部变量概念和使用方式。

二．实验内容：

1. 运行调试第2章编程示例2-5减法游戏；完成练习题2.5.1，2.5.2和2.5.3；
2. 运行调试第4章编程示例4-3素因数；完成练习题4.3.1，4.3.2，4.3.3；
3. 运行调试第4章编程示例4-5汉诺塔；完成练习题4.5.1，4.5.2。

三．示例代码：

　　1.第2章编程示例2-5减法游戏:

#include <iostream>

using namespace std;

int main() { int total, n; cout << "Welcome to NIM. Pick a starting total: "; cin >> total; while (true) {

// Pick best response and print results.

if ((total % 3) == 2) { total = total - 2; cout << "I am subtracting 2." << endl; } else { total--; cout << "I am subtracting 1." << endl; } cout << "New total is " << total << endl; if (total == 0) { cout << "I win!" << endl; break; }

// Get user's response; must be 1 or 2.

cout << "Enter number to subtract (1 or 2): "; cin >> n; while (n < 1 || n > 2) { cout << "Input must be 1 or 2." << endl; cout << "Re-enter: " << endl; cin >> n; } total = total - n; cout << "New total is " << total << endl; if (total == 0) { cout << "You win!" << endl; break; } } system("PAUSE"); return 0; }

　　2. 第4章编程示例4-3素因数：

#include <math.h> #include <iostream> using namespace std;

void get_divisors(int n);

int main() { int n;

cout << "Enter a number and press ENTER: "; cin >> n;

get_divisors(n);

cout << endl; system("PAUSE"); return 0; }

// Get divisors function // This function prints all the divisors of n, // by finding the lowest divisor, i, and then // rerunning itself on n/i, the remaining quotient.

void get_divisors(int n) { int i; double sqrt_of_n = sqrt((double) n);

for (i = 2; i <= sqrt_of_n; i++) if (n % i == 0) { // If i divides n evenly, cout << i << ", "; // Print i, get_divisors(n / i); // Factor n/i, return; // and exit. }

// If no divisor is found, then n is prime; // Print n and make no further calls.

cout << n; }

　　3.第4章编程示例4-5汉诺塔：

#include <cstdlib> #include <iostream>

using namespace std; void move_rings(int n, int src, int dest, int other);

int main() { int n = 3; // Stack is 3 rings high move_rings(n, 1, 3, 2); // Move stack 1 to stack 3 system("PAUSE"); return 0; }

void move_rings(int n, int src, int dest, int other) { if (n == 1) { cout << "Move from "<< src <<" to "<< dest << endl; } else { move_rings(n - 1, src, other, dest); cout << "Move from "<< src <<" to "<< dest << endl; move_rings(n - 1, other, dest, src); } }