Loops execute the same code repeatedly as long as a condition is true.
In PHP, we have while, do-while, for, and foreach loop.
while loops through a block of code as long as the condition is true.
Syntax
while (condition is true) {
// do something
}
Example
$i = 1
while ($i <= 10) {
echo $i++;
}
// Output: 12345678910
do...while loops through a block of code once, and repeats the loop as long as the condition is true.
Syntax
do {
// do something
} while (condition is true);
Example
$i = 2;
do {
echo $i;
} while ($i < 1);
// Output: 2
for loop loops through a block of code a specified number of times.
Syntax
for (init counter; condition; increment counter) {
// do something
}
Example
for ($i = 0; $i <= 5; $i++) {
echo $i;
}
// Output: 012345
Looping through an array
$array = [1, 2, 3, 4];
for ($i = 0; $i < count($array); $i++) {
echo $array[$i];
}
// Output: 1234
We can assign a variable to the array length to improve the performance, especially if an array has many items.
$array = [1, 2, 3, 4];
$length=count($array);
for ($i = 0; $i < $length; $i++) {
echo $array[$i];
}
// Output: 1234
foreach loop can iterate over an array or object.
Syntax
foreach ($array as $value) {
// do something
}
Example
$languages = ["English", "German", "Spanish"];
foreach ($languages as $lang) {
echo "$lang <br>";
}
/*
English
German
Spanish
*/
$scores = ["English" => 9, "German" => 9.5, "Spanish" => 8];
foreach ($scores as $key => $value) {
echo "$key: $value <br>";
}
/*
English: 9
German: 9.5
Spanish: 8
*/
Loop through an associative array
We can use the function implode() or json_encode() to loop through an associative array.
$person = [
"name" => "Dev",
"email" => "dev@gmail.com",
"skills" => ["react", "php", "wordpress"],
];
/* Using json_encode
foreach ($person as $key => $value) {
echo $key.": ".json_encode($value)." <br>";
}
*/
// Using implode()
foreach ($person as $key => $value) {
if (is_array($value)) {
$value = implode (", ", $value);
}
echo "$key: $value <br>";
}
/* Output
name: Dev
email: dev@gmail.com
skills: react, php, wordpress
*/
The break statement ends the current loop and jumps to the statement immediately following the loop.
for ($count = 1; $count <= 10; $count++ ) {
if ( $count == 5 ) break;
echo "Count: $count";
}
echo "Done";
/* Output:
Count: 1
Count: 2
Count: 3
Count: 4
Done
*/
The continue statement ends the current iteration, jumps to the top of the loop, and starts the next iteration.
for($count=1; $count<=10; $count++ ) {
if ( ($count % 2) == 0 ) continue;
echo "Count: $count\n";
}
echo "Done\n";
/* Output:
Count: 1
Count: 3
Count: 5
Count: 7
Count: 9
Done
*/