将"for"转换为循环到"while"循环环形 [英] Converting "for" loop to "while" loop

问题描述

我目前正在从事学期工作，这是我的一部分代码.如您所见，我在使用结构的地方有一些if语句的for循环.我当时正在考虑将此for循环转换为while循环，但是我不太确定该怎么做.也许有人可以给我提示?

I´m currently working on my semester work and this is a piece of my code. As you can see there is a for loop with some if statements where I am working with a structure. I was thinking of converting this for loop onto a while loop but I´m not quite sure how. Maybe someone may give me a hint?

for(X = 1; X <= 100; X++) 
        {
          if(structure[X].number == -1)
          {
            structure[X].number = number;
            structure[X].first_info = position;
            structure[X].second_info = position;
            break;
          }
          if(structure[X].number == number)
          {
            if(structure[X].first_info == -1) 
              structure[X].first_info = position;
              structure[X].second_info = position;
              break;
          }
        }

推荐答案

所有基本循环都包含三个组成部分:

All basic loops have three components:

• 初始值设定项(分配给变量的初始值)
• 条件(我们要检查的值以保持循环状态)
• 修饰符(用于修改变量的内容)

在for循环中，您会注意到这里的所有三个:

With a for loop you notice all three of those here:

for(X = 1; X <= 100; X++) 

括号中的第一个成分是初始化程序(X = 1)，下一个成分是条件(X< = 100)，最后一个成分是修饰符(X ++).

The first component in the parentheses is an initializer (X=1), the next component is the condition (X <= 100), and the last component is the modifier (X++).

我们可以在while循环中使用完全相同的组件.我们只是将它们放置在不同的位置:

We can use the exact same components with a while loop. We just place them differently:

int x = 1; //our intializer
while (x <= 100){ //our condition
      if(structure[X].number == -1)
      {
        structure[X].number = number;
        structure[X].first_info = position;
        structure[X].second_info = position;
        break;
      }
      if(structure[X].number == number)
      {
          if(structure[X].first_info == -1){
              structure[X].first_info = position;
          }
          structure[X].second_info = position;
          break;
      }
      x++; //our modifier
   }

话虽如此，C中的数组始终从索引0开始.我将代码保持不变，但是通常，无论您使用的是for循环还是while循环，您都需要按以下方式更改初始化程序和条件:

With that said, arrays in C always start at index 0. I kept your code the same as you had it, but generally whether you are using a for loop or while loop you will want to change your initializer and condition as follows:

• 您的初始值设定项应为x = 0(而不是x = 1)
您的条件可能应该是x<100或x< = 99(不是x< = 100)

• your initializer should likely be x = 0 (not x = 1)
• your condition should likely be either x < 100 or x <= 99 (not x <= 100)

这是因为包含100个项目的数组将具有从0到99的索引.

This is because an array of 100 items will have indexes 0 to 99.

还有两点:

在像这样的索引数组中进行计数时，通常将代码作为for循环而不是while循环更容易阅读.您是否有理由要使用while循环?

When counting through an indexed array like this the code is usually easier to read as a for loop rather than a while loop. Is there a reason that you were wanting to use a while loop instead?

根据您的缩进，尚不清楚最后一个if子句中应包含什么内容.我在您的最后一个if子句中添加了花括号，以使其更易于阅读，但是花括号中可能还应该包含其他行?

Based on your indentation it was unclear what should be included in the last if clause. I have added braces to your last if clause to make it easier to read, but maybe other lines should have been included in the braces as well?

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