PHP, Structures and Functions, Fundamental Syntaxes

$var

Variable to be converted to STRING.

A STRING literal can be specified in four different ways:

TYPE	STRING
SINGLE QUOTED	' STRING '
DOUBLE QUOTED	" STRING "
HEREDOC SYNTAX	<<<EOT STRING of multiple lines EOT;
NEWDOC SYNTAX	<<<'EOD' STRING of multiple lines EOD;"
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This function returns a STRING value when it tests the following variable types:

STRING, NUMERIC, BOOLEAN, ARRAY, NULL, RESOURCE or OBJECT.

A STRING, as we know, is any set of characters, each character occupying 1 byte.

This means that PHP does not offer native UNICODE support.

Since PHP 7.0.0, there are no particular restrictions regarding the length of a string on 64-bit builds.

On 32-bit builds and in earlier versions, a string can be as large as up to 2GB, (2147483647 bytes maximum).

If the STRING is delimited by DOUBLE QUOTES, PHP will interpret the following escape sequences as special characters:

ESCAPED CHARACTER	MEANING
\n	Linefeed (LF or 0x0A = 10 in ASCII)
\r	Carriage return (CR or 0x0D = 13 in ASCII)
\t	Horizontal tab HT or 0x09 = 9 in ASCII)
\v	Vertical tab (VT or 0x0B = 11 in ASCII) (since PHP 5.2.5)
\e	Escape (ESC or 0x1B = 27 in ASCII) (since PHP 5.4.4)
\f	Form feed FF or 0x0C = 12 in ASCII) (since PHP 5.2.5)
\\	BACKSLASH
\$	DOLLAR SIGN
\'	SINGLE-QUOTE
\"	DOUBLE-QUOTE
\[0-7]{1,3}	The sequence of characters matching the regular expression is a character in octal notation, which silently overflows to fit in a byte (e.g. "\400" === "\000")
\x[0-9A-Fa-f]{1,2}	The sequence of characters matching the regular expression is a character in hexadecimal notation
\u{[0-9A-Fa-f]+}	The sequence of characters matching the regular expression is a Unicode codepoint, which will be output to the string as that codepoint's UTF-8 representation (added in PHP 7.0.0)
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This function performs no formatting on the returned value.

If you are looking for a way to format a NUMERIC value as a STRING should wait for the moment when we will study other more appropriate functions.

EXERCISE


<?php
  
$xyz = "STRING DELIMITED BY \"DOUBLE QUOTATION MARKS\""; 
   
$str0 = 'STRING DELIMITED BY \'SINGLE QUOTATION MARKS\''; 
  
$carÇ = 'STRING DELIMITED BY SINGLE "QUOTATION MARKS"'; 
  
$_alo = "STRING DELIMITED BY DOUBLE 'QUOTATION MARKS'"; 
  
$rquo = "&nbsp;&nbsp;&raquo;&nbsp;&nbsp;"; 
  
$str01 = "1AnVXY234";  
  
$str02 = "1234567";

// HEREDOC
$str03h = <<<EOD
Easy come, easy go.\n\r<br>
If you can’t beat them, join them.\n\r<br>
Life begins at forty.\n\r<br>
Two heads are better than one. 
EOD;

$str04h = <<<EOT
In PHP there are TWO types
of variables:
INTERNAL, (predefined).
OF USER: (user-defined).
EOT;

// NOWDOC
$str03n = <<<'EOD'
Easy come, easy go.
If you can’t beat them, join them.
Life begins at forty.
Two heads are better than one. 
EOD;

$str04n = <<<'EOT'
In PHP there are TWO types
of variables:<br>
INTERNAL, (predefined)<br>
and<br>
OF USER: (user-defined).
EOT;


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

echo strval($carÇ) . '<br><br>' . 
              strval($_alo) . '<br><br>' . strval($rquo) . 
                   '<br><br>' . strval($str01) . '<br><br>' . 
                          strval($str02) . '<br><br>' . strval($str03h) . 
                                  '<br><br>' . strval($str04n) . '<br><br>';

?>

RESULT

STRING DELIMITED BY SINGLE "QUOTATION MARKS"

STRING DELIMITED BY DOUBLE 'QUOTATION MARKS'

»

1AnVXY234

1234567

Easy come, easy go.
If you can’t beat them, join them.
Life begins at forty.
Two heads are better than one.

In PHP there are TWO types of variables:
INTERNAL, (predefined)
and
OF USER: (user-defined).

EXERCISE


<?php

$vv02a = [ 'c' => 299792458, 'G' => 6.67428E-11 ]; 

var_dump(strval($vv02a));
echo '<br><br>';

$vv02b = [ 2, 8, 18, 32, 32, 18, 8 ];

var_dump(strval($vv02b));
echo '<br><br>';

$vv02c = $_SERVER['HTTP_ACCEPT_LANGUAGE'];

var_dump(strval($vv02c));
echo '<br><br>';

$vv02d = M_E;

var_dump(strval($vv02d));
echo '<br><br>';

$vv02e = 1.6e-19; 

var_dump(strval($vv02e));
echo '<br><br>';

$vv02f = null;

var_dump(strval($vv02f));
echo '<br><br>';

$vv02g = FALSE; 

var_dump(strval($vv02g));

?>