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==An Escape==



<source lang="html4strict">

\ indicates the escape character.

</source>

==Check string password==



<source lang="html4strict">

<?php
$GoodPassword = "asdfg";
$password = "asdf";
if ($password == $GoodPassword){
print "Password verified!\n";
}
?>

</source>

==Combine an expression with a string==



<source lang="html4strict">

<?
$centimeters = 212;
print "the width is ".($centimeters/100)." meters";
?>

</source>

==Comparing strings==



<source lang="html4strict">

<?
$word = "baa";
if ($word < "baa") {
print "Your word probably starts with "A".";
}
if ($word >= "zoo") {
print "Your word could be zoo or zymurgy, but not zone.";
}
?>

</source>

==Comparing strings with the equality operator==



<source lang="html4strict">

<?
if ("p@demo.ru" == "p@demo.ru") {
print "Welcome, Mr. President.";
}
?>

</source>

==curly offset syntax==



<source lang="html4strict">

<?php
$thing = "php";
echo $thing;
echo " ";
echo $thing{0};
echo $thing{1};
echo $thing{2};
?>

</source>

==Escape Characters in PHP==



<source lang="html4strict">

Escape String Resulting Character

\n Linefeed character

\r Carriage return character

\t Horizontal escape character escape character escape character escape character escape character tab character

\\ The backslash character

\$ The $ character

\" The single-quote character

\" The double-quote character

\### ASCII character (octal)

\x## ASCII character (hexadecimal)

</source>

==Escape Characters That Act As Anchors==



<source lang="html4strict">

Character Matches

\A Beginning of string

\b Word boundary

\B Not a word boundary

\Z End of string (matches before final newline or at end of string)

\z End of string (matches only at very end of string)

</source>

==Escape sequences and their meanings (continued)==



<source lang="html4strict">

\" Print the next character as a double quote rather than treating it as a string terminator

\" Print the next character as a single quote rather than treating it as a string terminator

\n Print a new line character

\t Print a tab character

\r Print a carriage return (used primarily on Windows)

\$ Print the next character as a dollar rather than treating it as part of a variable name

\\ Print the next character as a backslash rather than treating it as an escape character

Here is a code example of these escape sequences in action:
<?php
$MyString = "This is an \"escaped\" string";
$MySingleString = "This \"will\" work";
$MyNonVariable = "I have \$zilch in my pocket";
$MyNewline = "This ends with a line return\n";
$MyFile = "c:\\windows\\system32\\myfile.txt";
?>

</source>

==Getting an individual byte in a string==



<source lang="html4strict">

<?
$neighbor = "tester";
print $neighbor[3];
?>

</source>

==Indexing Strings==



<source lang="html4strict">

<?php
$test = "test";
print $test[0];
print $test[2];
?>

</source>

==PHP 5 Substring Functions==



<source lang="html4strict">

Function Description
substr_count() Counts the number of substring occurrences
strstr() Finds the first occurrence of a string
strchr() Can be used as an alias of strstr()
strrchr() Finds the last occurrence of a character in a string
stristr() Performs the same functionality as strstr() but is case-insensitive
substr_replace() Replaces text within a portion of a string
strops() Finds the position of the first occurrence of a string
substr() Returns a piece of a string

</source>

==Processing each byte in a string==



<source lang="html4strict">

<?php
$string = "Processing each byte in a string.";
$vowels = 0;
for ($i = 0, $j = strlen($string); $i < $j; $i++) {
if (strstr("aeiouAEIOU",$string[$i])) {
$vowels++;
}
}
?>

</source>

==Some string examples==



<source lang="html4strict">

<?php
$str = "This is a string";
$str = $str . " with some more text";
$str .= " and a newline at the end.\n";
$num = 9;
$str = "Number: $num";
$num = 9;
$str = "Number: $num";
$str = "This is a test.";
$first = $str[0];

$str = "This is still a test.";
$last = $str[strlen($str)-1];
?>

</source>

==Supported String Delimiters==



<source lang="html4strict">

CHARACTER REPRESENTATION

\n Newline

\r Carriage return

\t Horizontal tab

\\ Backslash

\$ Dollar sign

\" Double-quotation mark

\[0?7]{1,3} Octal notation regular expression pattern

\x[0?9A?Fa?f]{1,2} Hexadecimal notation regular expression pattern

</source>

==Using Escaped Characters==



<source lang="html4strict">

<?php
/* The same properly formatted string*/
$variable = "Do you know what \"escaped\" characters are?";
/* Prints the "a" character using hexadecimal */
$variable = "\x41 is the "a" character";
?>

</source>

==Using {x} notation with strings to read or write individual characters==



<source lang="html4strict">

$mystr = "Jello, world?";
$mystr{0} = "H";
$mystr{12} = "!";
print $mystr;

</source>

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