[c++] Endless loop in C/C++

The idiom designed into the C language (and inherited into C++) for infinite looping is for(;;): the omission of a test form. The do/while and while loops do not have this special feature; their test expressions are mandatory.

for(;;) does not express "loop while some condition is true that happens to always be true". It expresses "loop endlessly". No superfluous condition is present.

Therefore, the for(;;) construct is the canonical endless loop. This is a fact.

All that is left to opinion is whether or not to write the canonical endless loop, or to choose something baroque which involves extra identifiers and constants, to build a superfluous expression.

Even if the test expression of while were optional, which it isn't, while(); would be strange. while what? By contrast, the answer to the question for what? is: why, ever---for ever! As a joke some programmers of days past have defined blank macros, so they could write for(ev;e;r);.

while(true) is superior to while(1) because at least it doesn't involve the kludge that 1 represents truth. However, while(true) didn't enter into C until C99. for(;;) exists in every version of C going back to the language described in the 1978 book K&R1, and in every dialect of C++, and even related languages. If you're coding in a code base written in C90, you have to define your own true for while (true).

while(true) reads badly. While what is true? We don't really want to see the identifier true in code, except when we are initializing boolean variables or assigning to them. true need not ever appear in conditional tests. Good coding style avoids cruft like this:

if (condition == true) ...

in favor of:

if (condition) ...

For this reason while (0 == 0) is superior to while (true): it uses an actual condition that tests something, which turns into a sentence: "loop while zero is equal to zero." We need a predicate to go nicely with "while"; the word "true" isn't a predicate, but the relational operator == is.

Examples related to c++

Method Call Chaining; returning a pointer vs a reference? How can I tell if an algorithm is efficient? Difference between opening a file in binary vs text How can compare-and-swap be used for a wait-free mutual exclusion for any shared data structure? Install Qt on Ubuntu #include errors detected in vscode Cannot open include file: 'stdio.h' - Visual Studio Community 2017 - C++ Error How to fix the error "Windows SDK version 8.1" was not found? Visual Studio 2017 errors on standard headers How do I check if a Key is pressed on C++

Examples related to c

conflicting types for 'outchar' Can't compile C program on a Mac after upgrade to Mojave Program to find largest and second largest number in array Prime numbers between 1 to 100 in C Programming Language In c, in bool, true == 1 and false == 0? How I can print to stderr in C? Visual Studio Code includePath "error: assignment to expression with array type error" when I assign a struct field (C) Compiling an application for use in highly radioactive environments How can you print multiple variables inside a string using printf?

Examples related to loops

How to increment a letter N times per iteration and store in an array? Angular 2 Cannot find control with unspecified name attribute on formArrays What is the difference between i = i + 1 and i += 1 in a 'for' loop? Prime numbers between 1 to 100 in C Programming Language Python Loop: List Index Out of Range JavaScript: Difference between .forEach() and .map() Why does using from __future__ import print_function breaks Python2-style print? Creating an array from a text file in Bash Iterate through dictionary values? C# Wait until condition is true

Examples related to infinite-loop

how do I create an infinite loop in JavaScript break statement in "if else" - java Endless loop in C/C++ How to run the Python program forever? How to get out of while loop in java with Scanner method "hasNext" as condition? Python - A keyboard command to stop infinite loop? How to create an infinite loop in Windows batch file? Which is the correct C# infinite loop, for (;;) or while (true)?