Php for loop code#

For example, in the for statement in the following pseudocode fragment, when calculating the new value for A(i), except for the first (with i = 2) the reference to A(i - 1) will obtain the new value that had been placed there in the previous step. Some languages offer a for-loop that acts as if processing all iterations in parallel, such as the for all keyword in FORTRAN 95 which has the interpretation that all right-hand-side expressions are evaluated before any assignments are made, as distinct from the explicit iteration form. Some languages have this in addition to another for-loop syntax notably, PHP has this type of loop under the name for each, as well as a three-expression for-loop (see below) under the name for. Where some_iterable_object is either a data collection that supports implicit iteration (like a list of employee's names), or may in fact be an iterator itself. Here is an example of the C-style traditional for-loop in Java.įor item in some_iterable_object : do_something () do_something_else () The loop is then repeated if the condition evaluates to true. The advancement to the next iteration part is performed exactly once every time the loop ends.

Php for loop code#

If the condition is true, then the lines of code inside the loop are executed. The condition part checks a certain condition and exits the loop if false, even if the loop is never executed. If multiple variables are declared, they should all be of the same type. In the initialization part, any variables needed are declared (and usually assigned values). This type of 'semicolon loops' came from B programming language and it was originally invented by Stephen Johnson.

It requires 3 parts: the initialization ( loop variant), the condition, and the advancement to the next iteration. Some languages require a separate declaration of the control variable, some do not.Īnother form was popularized by the C programming language. An optional step-value (an increment or decrement ≠ 1) may also be included, although the exact syntaxes used for this differs a bit more between the languages. last do statementĭepending on the language, an explicit assignment sign may be used in place of the equal sign (and some languages require the word int even in the numerical case).

5.20 1991: Oberon-2, Oberon-07, or Component Pascalįor i = first to last do statement (* or just *) for i = first.

5 Timeline of the for-loop syntax in various programming languages.

In Fortran and PL/I, the keyword DO is used for the same thing and it is called a do-loop this is different from a do-while loop. The loop body is executed 'for' the given values of the loop variable, though this is more explicit in the ALGOL version of the statement, in which a list of possible values and/or increments can be specified. The term in English dates to ALGOL 58 and was popularized in the influential later ALGOL 60 it is the direct translation of the earlier German für, used in Superplan (1949–1951) by Heinz Rutishauser, who also was involved in defining ALGOL 58 and ALGOL 60. The name for-loop comes from the word for, which is used as the keyword in many programming languages to introduce a for-loop. For-loops can be thought of as shorthands for while-loops which increment and test a loop variable. For-loops are typically used when the number of iterations is known before entering the loop. The header often declares an explicit loop counter or loop variable, which allows the body to know which iteration is being executed. There are other possibilities, for example COBOL which uses 'PERFORM VARYING'.Ī for-loop has two parts: a header specifying the iteration, and a body which is executed once per iteration. Various keywords are used to specify this statement: descendants of ALGOL use 'for', while descendants of Fortran use 'do'. In computer science, a for-loop (or simply for loop) is a control flow statement for specifying iteration, which allows code to be executed repeatedly.