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. This is more explicit in ALGOL versions of the for statement where a list of possible values and increments can be specified. The loop body is executed "for" the given values of the loop variable. Rutishauser was involved in defining ALGOL 58 and ALGOL 60. It is the direct translation of the earlier German für and was used in Superplan (1949–1951) by Heinz Rutishauser. The term in English dates to ALGOL 58 and was popularized in ALGOL 60. For is used as the keyword in many programming languages to introduce a for-loop. The name for-loop comes from the word for. There are other possibilities, for example COBOL which uses "PERFORM VARYING". Various keywords are used to indicate the usage of a for loop: descendants of ALGOL use "for", while descendants of Fortran use "do".
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. This allows the body to know which iteration is being executed. The header often declares an explicit loop counter or loop variable.
For loop in php code#
The header defines the iteration and the body is the code that is executed once per iteration.
Specifically, a for loop functions by running a section of code repeatedly until a certain condition has been satisfied.įor-loops have two parts: a header and a body. In computer science a for-loop or for loop is a control flow statement for specifying iteration.
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