Loops are an important part of the programming languages. For
and While
loops are used for decades in different programming languages. Foreach
provides similar functionality in a more elegant way by iterating over the given list. In this tutorial, we will examine foreach
in different programming languages like PHP, JavaScript, Java, C# and Python.
PHP Foreach
PHP provides foreach in order to iterate over given arrays. There is two main usage syntax about PHP foreach.
Value Syntax
In value syntax, we will provide just the array which is named ARRAY_EXPRESSION and the VALUE. We will write operations to the STATEMENT
foreach (ARRAY_EXPRESSION as $VALUE)
STATEMENT
In this example, we will print array values to the standard output.
<?php
$arr = array(1, 2, 3, 4);
foreach ($arr as $value) {
echo $value;
}
?>
Key, Value Syntax
In Key and Value syntax will also get the key from the array and use it in the foreach.
foreach (ARRAY_EXPRESSION as $KEY=>$VALUE)
STATEMENT
In this example, we will print key and values into standard output
<?php
$arr = array(1, 2, 3, 4);
foreach ($arr as $key=>$value) {
echo $value;
}
?>
JavaScript Foreach
JavaScript is a very extensible language where most of the features are provided by objects. foreach
is also provided by the object which is an array. It has the following syntax.
JavaScript Foreach Syntax
ARRAY.forEach(function(VALUE) {
STATEMENT;
});
In this example, we will iterate over array named arr
and print to the console.
var arr = ['a', 'b', 'c','d','e']
arr.forEach(function(element) {
console.log(element);
});
Java Foreach
Java programming language actually does not provides native foreach
keyword. But we can use other elements of Java like List
, ArrayList
and for
.
For Syntax
We will use List
and for
to create foreach
mechanism. TYPE is VALUE type and we will provide LIST.
for(TYPE VALUE:LIST){
STATEMENT
}
We will iterate over string list and we will print to the standard output.
List<String> items = new ArrayList<>("A","B","C","D");
for(String item : items){
System.out.println(item);
}
Foreach Syntax
After Java 8 List
type provides forEach()
function. So we can create a LIST and then iterate over elements with forEach()
function. We will also use a lambda expression.
List<String> items = new ArrayList<>("A","B","C","D");
items.forEac(item->System.out.println(item));
C# Foreach
C # provides the foreach
statement in a native way. We will provide the LIST with the in
keyword and set ELEMENT with the given TYPE.
foreach (TYPE ELEMENT in LIST){
STATEMENT
}
In this example, we will iterate over an integer list named lst
.
var lst= new List<int> { 0, 1, 1, 2, 3, 5, 8, 13 };
foreach (int element in lst) {
Console.WriteLine($"Element {element}");
}
Python Foreach
Python programming language does not provide the foreach
keyword but the actual implementation of the for
in Python is hte same as the foreach
. We can iterate over List
, Array
, Dictionary
type in python with for
like below.
for ELEMENT in LIST:
STATEMENT
In this example, we will iterate over list named lst
.
lst=[1,2,3,4,5]
for element in lst:
print element