forloop

Forloop is a control flow construct used in many programming languages to repeat a block of code. It can implement a fixed number of iterations or traverse elements of a collection. A typical for loop combines initialization, a termination condition, and an update step for the loop variable.

In C, C++, Java, JavaScript and similar languages, the common form is: for (initialization; condition; update) { /* body */ }. The loop starts by performing initialization, then checks the condition before each iteration, executes the body, and finally applies the update before rechecking.

In languages such as Python, for loops iterate over iterables rather than using a counter explicitly. The syntax is: for item in iterable: do_something(item). Each value from the iterable becomes the loop variable in sequence.

Variants include the for-each or range-based forms, such as for (Type x : collection) in Java or for (auto x : range) in C++. Some languages offer a plain for with an index; others provide while or do-while loops for similar repetition.

Common considerations include avoiding off-by-one errors, ensuring termination, and being mindful of modifying the underlying collection during iteration. The performance impact is usually small and largely determined by the work done inside the loop and the language implementation.