C++ keyword: while

 

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C++ language

General topics
Preprocessor Comments	Keywords Escape sequences
Flow control
Conditional execution statements
if	switch
Iteration statements (loops)
for range-for (C++11)	while do-while
Jump statements
continue - break	goto - return
Functions
Function declaration
Lambda function expression
inline specifier
Dynamic exception specifications (until C++17*)
noexcept specifier (C++11)
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throw-expression try block	handler
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const/volatile decltype (C++11) auto (C++11)	constexpr (C++11) consteval (C++20) constinit (C++20)
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Default-initialization Value-initialization Zero-initialization Copy-initialization Direct-initialization	Aggregate initialization List-initialization (C++11)   Constant initialization Reference initialization

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Virtual function override specifier (C++11)   final specifier (C++11)	explicit (C++11) static
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Class template Function template	Template specialization Parameter packs (C++11)
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Inline assembly	History of C++

 

Keywords

alignas (C++11) alignof (C++11) and and_eq asm auto (*) bitand bitor bool break case catch char char8_t (C++20) char16_t (C++11) char32_t (C++11) class compl concept (C++20) const consteval (C++20)     constexpr (C++11) constinit (C++20) const_cast continue co_await (C++20) co_return (C++20) co_yield (C++20) decltype (C++11) default delete	do double dynamic_cast else enum explicit export extern false float for friend goto if inline int long mutable namespace new noexcept (C++11)     not not_eq nullptr (C++11) operator or or_eq private protected public register	reinterpret_cast requires (C++20) return short signed sizeof (*) static static_assert (C++11) static_cast struct switch template this thread_local (C++11) throw true try typedef typeid typename union unsigned using virtual void volatile wchar_t while xor xor_eq
Identifiers with special meaning
final (C++11) import (C++20)	module (C++20) override (C++11)

 

Usage

• while loop: as the declaration of the loop
• do-while loop: as the declaration of the terminating condition of the loop

Example

Run this code

#include <iostream>
 
int main() noexcept
{
    int i{3};
 
    // The following 'while' loop statement:
    // 1. (condition) Checks if value of the variable 'i' is greater than zero
    //                and if not, ends the loop execution with end of this point.
    //                Post-decrements the variable 'i' (decreases its value by 1).
    // 2. (statement) Writes out a current value of the variable 'i' to the stdout.
    // 3.             Returns to the point 1 (condition).
 
    while (i --> 0)     // condition: i-- > 0
        std::cout << i; // statement: std::cout << i;
}

Output:

210

See also

• if statement: if, else

constexpr if statement: constexpr (constexpr if statement)	(since C++17)
consteval if statement: consteval (consteval if statement)	(since C++23)

• switch statement: switch, case
• default (as case label declaration) etc: default
• goto statement: goto
• continue statement: continue
• break statement: break
• return statement: return

co_return statement (return from a coroutine): co_return

(since C++20)

• do-while loop and while loop: do
• for loop and range-based for loop: for