foreach Loop comparison of several programming languages

foreach Loop comparison of several programming languages

The Foreach Loop, as the "enhanced version" of the "for" loop, has been widely used in several programming languages (Java, C #, PHP) because it can traverse array elements in a simpler way. In different languages, however, the specific form of the Foreach loop varies. Below, let's compare the specific structure and application examples of the Foreach loop in Java, C #, and PHP three languages:

1. The Foreach loop is provided after the java:jdk1.5

Syntax format:

for (type variablename:array|collection)

{

VariableName automatically iterates through each element;

}

Instance

Java code

public class Test1   {public           static void Main (string[] args)           {                   string[] names = {"Jerry", "Tom", "Spike"}; For                   (String name:names)                          SYSTEM.OUT.PRINTLN (name);         }  }

2. Php:php 4 introduces the foreach structure

Syntax Format 1:

foreach (array_expression as $value)

Statement

Iterates over the given array of array_expression. In each loop, the value of the current cell is assigned to the $value and the pointer inside the array moves forward one step (so the next cell in the next loop will be taken)

Syntax Format 2:

foreach (array_expression as $key = $value)

Statement

In addition to the function of format 1, the key name of the current cell is assigned to the variable $key in each loop.

Starting with PHP 5, it is easy to modify the cells of an array by adding & to it before $value. This method assigns a value to a reference instead of copying a value.

PHP code

<?php    $arr = Array (1, 2, 3, 4);    foreach ($arr  as  & $value) {    $value = $value * 2;    }    $arr is now Array (2, 4, 6, 8)  ?>

3. C #: The Foreach method in C # is similar to the basic in Java, except that the foreach in C # is "in" (a colon in Java)

Syntax format:

foreach (type variableName in array)

{

VariableName automatically iterates through each element;

}

Example

C # code

Int[] num={1,2,3};  foreach (int i in arr)  {  System.Console.WriteLine (i);  }

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