Namespaces
Variants

C++ keyword: while

From cppreference.net
C++ language
General topics
Flow control
Conditional execution statements
Iteration statements (loops)
Jump statements
Functions
Function declaration
Lambda function expression
inline specifier
Dynamic exception specifications ( until C++17* )
noexcept specifier (C++11)
Exceptions
Namespaces
Types
Specifiers
constexpr (C++11)
consteval (C++20)
constinit (C++20)
Storage duration specifiers
Initialization
Expressions
Alternative representations
Literals
Boolean - Integer - Floating-point
Character - String - nullptr (C++11)
User-defined (C++11)
Utilities
Attributes (C++11)
Types
typedef declaration
Type alias declaration (C++11)
Casts
Memory allocation
Classes
Class-specific function properties
Special member functions
Templates
Miscellaneous

用法

  • while 循环:作为循环的声明
  • do-while 循环:作为循环终止条件的声明

示例

#include <iostream>
int main() noexcept
{
    int i{3};
    // 以下 'while' 循环语句:
    // 1. (条件) 检查变量 'i' 的值是否大于零
    //                若否,则在此点结束循环执行。
    //                对变量 'i' 执行后置递减(将其值减1)。
    // 2. (语句) 将变量 'i' 的当前值写入 stdout。
    // 3.             返回至第1点(条件)。
    while (i --> 0)     // condition: i-- > 0
        std::cout << i; // statement: std::cout << i;
}

输出:

210

参见

(C++17 起)
(C++23 起)
(自 C++20 起)