echo
echo
Output one or more strings
void **echo** string $expressions
Outputs one or more expressions, with no additional newlines or spaces.
is not a function but a language construct.
Its arguments are a list of expressions following the
keyword, separated by commas, and not delimited by parentheses.
Unlike some other language constructs, does not have
any return value, so it cannot be used in the context of an expression.
echo``echo``echo
also has a shortcut syntax, where you can
immediately follow the opening tag with an equals sign. This syntax is available even with the configuration setting disabled.
echoshort_open_tag```php
I have =$foo?> foo.
The major differences to are that
accepts multiple arguments and doesn't have a return value.
`print``echo`
`expressions`
One or more string expressions to output, separated by commas.
Non-string values will be coerced to strings, even when
is enabled.
the
strict_types directive
return.void
**Voorbeeld: examples**
```php
<?php
echo "echo does not require parentheses.";
// Strings can either be passed individually as multiple arguments or
// concatenated together and passed as a single argument
echo 'This ', 'string ', 'was ', 'made ', 'with multiple parameters.', "\n";
echo 'This ' . 'string ' . 'was ' . 'made ' . 'with concatenation.' . "\n";
// No newline or space is added; the below outputs "helloworld" all on one line
echo "hello";
echo "world";
// Same as above
echo "hello", "world";
echo "This string spans
multiple lines. The newlines will be
output as well";
echo "This string spans\nmultiple lines. The newlines will be\noutput as well.";
// The argument can be any expression which produces a string
$foo = "example";
echo "foo is $foo"; // foo is example
$fruits = ["lemon", "orange", "banana"];
echo implode(" and ", $fruits); // lemon and orange and banana
// Non-string expressions are coerced to string, even if declare(strict_types=1) is used
echo 6 * 7; // 42
// However, the following examples will work:
($some_var) ? print 'true' : print 'false'; // print is also a construct, but
// it is a valid expression, returning 1,
// so it may be used in this context.
echo $some_var ? 'true': 'false'; // evaluating the expression first and passing it to echo
?>
Voorbeeld: is not an expression
<?php
// Because echo does not behave as an expression, the following code is invalid.
($some_var) ? echo 'true' : echo 'false';
?>
Opmerking: > ### Using with parentheses
Surrounding a single argument to with parentheses will not raise a syntax error, and produces syntax which looks like a normal function call. However, this can be misleading, because the parentheses are actually part of the expression being output, not part of the syntax itself.
echo``echoVoorbeeld: Using Parentheses<?php echo "hello", PHP_EOL; // outputs "hello" echo("hello"), PHP_EOL; // also outputs "hello", because ("hello") is a valid expression echo(1 + 2) * 3, PHP_EOL; // outputs "9"; the parentheses cause 1+2 to be evaluated first, then 3*3 // the echo statement sees the whole expression as one argument echo "hello", " world", PHP_EOL; // outputs "hello world" echo("hello"), (" world"), PHP_EOL; // outputs "hello world"; the parentheses are part of each expression ?>Voorbeeld: Invalid Expression
<?php echo("hello", " world"), PHP_EOL; // Throws a Parse Error because ("hello", " world") is not a valid expression ?>
Tip: > Passing multiple arguments to can avoid complications arising from the precedence of the concatenation operator in PHP. For instance, the concatenation operator has higher precedence than the ternary operator, and prior to PHP 8.0.0 had the same precedence as addition and subtraction:
echo<?php // Below, the expression 'Hello ' . isset($name) is evaluated first, // and is always true, so the argument to echo is always $name echo 'Hello ' . isset($name) ? $name : 'John Doe' . '!'; // The intended behaviour requires additional parentheses echo 'Hello ' . (isset($name) ? $name : 'John Doe') . '!'; // In PHP prior to 8.0.0, the below outputs "2", rather than "Sum: 3" echo 'Sum: ' . 1 + 2; // Again, adding parentheses ensures the intended order of evaluation echo 'Sum: ' . (1 + 2);If multiple arguments are passed in, then parentheses will not be required to enforce precedence, because each expression is separate:
<?php echo "Hello ", isset($name) ? $name : "John Doe", "!"; echo "Sum: ", 1 + 2;
print``printf``flushWays to specify literal strings