PHP TutorialCompile PHP ExtensionsContributing to the PHP CoreContributing to the PHP ManualCreate PDF files in PHPInstalling a PHP environment on WindowsPHP Alternative Syntax for Control StructuresPHP APCuPHP Array iterationPHP ArraysPHP Asynchronous programmingPHP Autoloading PrimerPHP BC Math (Binary Calculator)PHP Built in serverPHP CachePHP Classes and ObjectsPHP ClosurePHP Coding ConventionsPHP Command Line Interface (CLI)PHP CommentsPHP Common ErrorsPHP Compilation of Errors and WarningsPHP Composer Dependency ManagerPHP ConstantsPHP Control StructuresPHP CookiesPHP CryptographyPHP DateTime ClassPHP DebuggingPHP Dependency InjectionPHP Design PatternsPHP Docker deploymentPHP Exception Handling and Error ReportingPHP Executing Upon an ArrayPHP File handlingPHP Filters & Filter FunctionsPHP Functional ProgrammingPHP FunctionsPHP GeneratorsPHP Headers ManipulationPHP How to break down an URLPHP How to Detect Client IP AddressPHP HTTP AuthenticationPHP Image Processing with GDPHP ImagickPHP IMAPPHP Installing on Linux/Unix EnvironmentsPHP JSONPHP LocalizationPHP LoopsPHP Machine learningPHP Magic ConstantsPHP Magic MethodsPHP Manipulating an ArrayPHP mongo-phpPHP Multi Threading ExtensionPHP MultiprocessingPHP MySQLiPHP MySQLi affected rows returns 0 when it should return a positive integerPHP NamespacesPHP Object SerializationPHP OperatorsPHP Output BufferingPHP Outputting the Value of a VariablePHP Parsing HTMLPHP Password Hashing FunctionsPHP PDOPHP PerformancePHP PHPDocPHP Processing Multiple Arrays TogetherPHP PSRPHP Reading Request DataPHP RecipesPHP ReferencesPHP ReflectionPHP Regular Expressions (regexp/PCRE)PHP Secure Remeber MePHP SecurityPHP Sending EmailPHP SerializationPHP SessionsPHP SimpleXMLPHP SOAP ClientPHP SOAP ServerPHP SocketsPHP SPL data structuresPHP SQLite3PHP StreamsPHP String formattingPHP String Parsing

PHP String formatting

From WikiOD

String interpolation[edit | edit source]

You can also use interpolation to interpolate (insert) a variable within a string. Interpolation works in double quoted strings and the heredoc syntax only.

$name = 'Joel';

// $name will be replaced with `Joel`
echo "<p>Hello $name, Nice to see you.</p>";
#                ↕
#>   "<p>Hello Joel, Nice to see you.</p>"

// Single Quotes: outputs $name as the raw text (without interpreting it)
echo 'Hello $name, Nice to see you.'; # Careful with this notation
#> "Hello $name, Nice to see you."

The complex (curly) syntax format provides another option which requires that you wrap your variable within curly braces {}. This can be useful when embedding variables within textual content and helping to prevent possible ambiguity between textual content and variables.

$name = 'Joel';

// Example using the curly brace syntax for the variable $name
echo "<p>We need more {$name}s to help us!</p>";
#> "<p>We need more Joels to help us!</p>"

// This line will throw an error (as `$names` is not defined)
echo "<p>We need more $names to help us!</p>";
#> "Notice: Undefined variable: names"

The {} syntax only interpolates variables starting with a $ into a string. The {} syntax does not evaluate arbitrary PHP expressions.

// Example tying to interpolate a PHP expression
echo "1 + 2 = {1 + 2}";
#> "1 + 2 = {1 + 2}"

// Example using a constant
define("HELLO_WORLD", "Hello World!!");
echo "My constant is {HELLO_WORLD}";
#> "My constant is {HELLO_WORLD}"

// Example using a function
function say_hello() {
    return "Hello!";
echo "I say: {say_hello()}";
#> "I say: {say_hello()}"

However, the {} syntax does evaluate any array access, property access and function/method calls on variables, array elements or properties:

// Example accessing a value from an array — multidimensional access is allowed
$companions = [0 => ['name' => 'Amy Pond'], 1 => ['name' => 'Dave Random']];
echo "The best companion is: {$companions[0]['name']}";
#> "The best companion is: Amy Pond"

// Example of calling a method on an instantiated object
class Person {
  function say_hello() {
    return "Hello!";

$max = new Person();

echo "Max says: {$max->say_hello()}";
#> "Max says: Hello!"

// Example of invoking a Closure — the parameter list allows for custom expressions
$greet = function($num) {
    return "A $num greetings!";
echo "From us all: {$greet(10 ** 3)}";
#> "From us all: A 1000 greetings!"

Notice that the dollar $ sign can appear after the opening curly brace { as the above examples, or, like in Perl or Shell Script, can appear before it:

$name = 'Joel';

// Example using the curly brace syntax with dollar sign before the opening curly brace
echo "<p>We need more ${name}s to help us!</p>";
#> "<p>We need more Joels to help us!</p>"

The Complex (curly) syntax is not called as such because it's complex, but rather because it allows for the use of 'complex expressions'. Read more about Complex (curly) syntax

Extracting/replacing substrings[edit | edit source]

Single characters can be extracted using array (square brace) syntax as well as curly brace syntax. These two syntaxes will only return a single character from the string. If more than one character is needed, a function will be required, i.e.- substr

Strings, like everything in PHP, are 0-indexed.

$foo = 'Hello world';

$foo[6]; // returns 'w'
$foo{6}; // also returns 'w'

substr($foo, 6, 1); // also returns 'w'
substr($foo, 6, 2); // returns 'wo'

Strings can also be changed one character at a time using the same square brace and curly brace syntax. Replacing more than one character requires a function, i.e.- substr_replace

$foo = 'Hello world';

$foo[6] = 'W'; // results in $foo = 'Hello World'
$foo{6} = 'W'; // also results in $foo = 'Hello World'

substr_replace($foo, 'W', 6, 1); // also results in $foo = 'Hello World'
substr_replace($foo, 'Whi', 6, 2); // results in 'Hello Whirled'
// note that the replacement string need not be the same length as the substring replaced