C++ 初学者指南 第一篇（11）

项目 1-2 生成一张从英尺到米的转换表
    这个项目将显示一张从英尺到米的转换表，其中用到了for循环，if语句和代码块。表格的起始为一英尺，终止为100英尺。每输出10英尺的转换表后，输出一个空行，这个是通过使用变量counter来实现的。边玲counter是用来表示行数的，请注意它的用法。
步骤：
1.创建一个新的文件，命名为FtoMTable.cpp。
2.文件中键入下面的程序：   

 #include <iostream>
    using namespace std;
    int main()
    {
        double f; // 用来存储英尺长度
        double m; //用来存储转换后的米的值
        int counter;
        counter = 0; // 用于统计行数，变量初始化为0
        for ( f =1.0; f <= 100; f++)
        {
            m = f /3.28; //英尺转换为米
            cout << f << " feet is " << m << " meters.\n";
            //循环每次都要把行数增加1
            counter++;
            //每10行输出一个空行
            //如果行数为10了，则需要输出一个空行
            if ( counter == 10 ) 
            {
                cout << "\n"; //输出空行
                counter = 0;  //重置行数计数器
            }
        }
        return 0;
    }    

3.注意我们是如何使用counter变量来实现每10行输出一个空行的。在for 循环外该变量被初始化为0。在for循环体内部，每做一次英尺到米的转换，counter 就增加1。当counter增加到10的时候，就输出一个空行，然后重置counter的值为0，重新开始上面的过程。
4.编译并运行上面的程序。下面是输出的一部分。注意程序输出的小数部分并不是很整齐。
  1 feet is 0.304878 meters.
  2 feet is 0.609756 meters.
  3 feet is 0.914634 meters.
  4 feet is 1.21951 meters.
  5 feet is 1.52439 meters.
  6 feet is 1.82927 meters.
  7 feet is 2.13415 meters.
  8 feet is 2.43902 meters.
  9 feet is 2.7439 meters.
  10 feet is 3.04878 meters.

  11 feet is 3.35366 meters.
  12 feet is 3.65854 meters.
  13 feet is 3.96341 meters.
  14 feet is 4.26829 meters.
  15 feet is 4.57317 meters.
  16 feet is 4.87805 meters.
  17 feet is 5.18293 meters.
  18 feet is 5.4878 meters.
  19 feet is 5.79268 meters.
  20 feet is 6.09756 meters.

  21 feet is 6.40244 meters.
  22 feet is 6.70732 meters.
  23 feet is 7.0122 meters.
  24 feet is 7.31707 meters.
  25 feet is 7.62195 meters.
  26 feet is 7.92683 meters.
  27 feet is 8.23171 meters.
  28 feet is 8.53659 meters.
  29 feet is 8.84146 meters.
  30 feet is 9.14634 meters.

  31 feet is 9.45122 meters.
  32 feet is 9.7561 meters.
  33 feet is 10.061 meters.
  34 feet is 10.3659 meters.
  35 feet is 10.6707 meters.
  36 feet is 10.9756 meters.
  37 feet is 11.2805 meters.
  38 feet is 11.5854 meters.
  39 feet is 11.8902 meters.
  40 feet is 12.1951 meters.
5.可以自己尝试修改上面的程序为每25行输出一个空行。