C++编程思想 第1卷 第3章 while语句

循环控制语句，重复执行到控制表达式的计数值为假
一开始就对表达式进行计算
在重复执行之前再次计算。

while可以更复杂

//: C03:Guess.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
// Guess a number (demonstrates "while")
#include <iostream>
using namespace std;

int main() {
  int secret = 15;
  int guess = 0;
  // "!=" is the "not-equal" conditional:
  while(guess != secret) { // Compound statement
    cout << "guess the number: ";
    cin >> guess;
  }
  cout << "You guessed it!" << endl;
  getchar();
} ///:~

输出
只有输到15 就可以猜到，要不然一直循环
control+c 有异常