之间＆QUOT差异;而＆QUOT;环和＆QUOT;做好而＆QUOT;循环 [英] Difference between "while" loop and "do while" loop

问题描述

什么是while循环之间的差异，while循环做。我曾经认为这两个是完全same.Then我碰到下面的一段code的传来：

What is the difference between while loop and do while loop. I used to think both are completely same.Then I came across following piece of code :

do {
        printf("Word length... ");
        scanf("%d", &wdlen);
    } while(wdlen<2);

这code完美的作品。它打印字长和tascans输入。但是，当我把它改成

This code works perfectly. It prints word length and tascans the input. But when I changed it to

while(wdlen<2){
        printf("Word length... ");
        scanf("%d", &wdlen);
    } 

它给出​​了一个空白屏幕。它不工作。因此，有两个回路之间存在一些功能上的差异。任何人都可以解释一下吗？先谢谢了。

It gives a blank screen. It do not work. So there is some functional difference between both loops. Can anybody explain it? Thanks in advance.

编辑：有没有在这两个其他任何区别

EDIT : Is there any other difference in these two ?

推荐答案

在做的，而一次循环检查，同时的条件之前执行循环的内容。

The do while loop executes the content of the loop once before checking the condition of the while.

而A ，而循环将执行内容之前先检查条件。

Whereas a while loop will check the condition first before executing the content.

在这种情况下会等待用户输入与scanf（）的，它绝不会在执行，而环路wdlen没有初始化，可能只包含这可能是一个垃圾值大于2

In this case you are waiting for user input with scanf(), which will never execute in the while loop as wdlen is not initialized and may just contain a garbage value which may be greater than 2.

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