在和while循环无循环的条件 [英] No loop condition in for and while loop

问题描述

while(cond) // fine
for(;cond;) //fine

但是当我删除条件部分

but when I remove the conditional part

while() //syntax compilation error 
for(;;) //Infinite loop

如何这些循环在内部实现？
或者说，如何做编译器（分析器）知道，在空状态，而是误差和为为无穷大？

我没有找到这个什么特别，我觉得像我这样的家伙（谁是初学者c）中可能有同样的困惑

I didn't find anything about this particularly, I think guys like me (who are beginner) in C might have same confusion

推荐答案

该标准要求为为循环中省略的条件是由一个非零常数代替：

The standard requires that the omitted condition for for loop is replaced by a non-zero constant:

从 C11 6.8.5.3 ：（重点煤矿）

6.8.5.3 for语句

6.8.5.3 The for statement

1语句（第1;前pression-2;前pression-3）
  声明行为如下：这位前pression前pression-2是
  控制所的每一个执行前评估前pression
  循环体。这位前pression前pression-3被评估为一个空白
  循环体的每次执行后的前pression。如果条款-1是一个
  声明，它声明的任何变量的作用域是余
  宣言和整个循环，包括其他两个
  前pressions;它是在执行顺序到达之前的第一
  控制前pression的评价。如果条款-1是
  前pression，它是作为一个空白的前pression前首先评估
  控制前pression.134的评价）

1 The statement for ( clause-1 ; expression-2 ; expression-3 ) statement behaves as follows: The expression expression-2 is the controlling expression that is evaluated before each execution of the loop body. The expression expression-3 is evaluated as a void expression after each execution of the loop body. If clause-1 is a declaration, the scope of any variables it declares is the remainder of the declaration and the entire loop, including the other two expressions; it is reached in the order of execution before the first evaluation of the controlling expression. If clause-1 is an expression, it is evaluated as a void expression before the first evaluation of the controlling expression.134)

2两个条款-1和前pression-3可以省略。被忽略的前pression-2是由一个非零常数取代。

由于对，而循环没有这样的要求（如果省略的情况），我相信，它留给编译执行。

Since there's no such requirement for while loop (if the condition is omitted), I believe, it's left to the implementation of compiler.

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