1. String functions

2. String Length strlen() Returns the length of a string str_word_count()
Count the number of words in a string

3. echo and print echo() Outputs strings print() Outputs a string
printf()
Outputs a formatted string
sprintf()
Writes a formatted string to a variable
fprintf()
Writes a formatted string to a specified output stream
vprintf()
vsprintf()
vfprintf()
number_format()
Formats a number with grouped thousands

4. printf( )
<?php $num1= ; echo "$num1<br/>"; printf("%f<br/>", $num1); printf("%.2f", $num1); // printf("%f<br/>%.2f", $num1, $num1); ?>

5. number_format() Price: NT$45,080 Number: 315 Total: NT$14,200,200.00
<?php
$price= 45080;
$num = 315;
$tot = $price * $num;
echo "Price: NT\$", number_format($price),"<br/>";
echo "Number: $num<br/>";
echo "Total: NT\$", number_format($tot, 2),"<br/>";
?>
Price: NT$45,080 Number: 315 Total: NT$14,200,200.00

6. Split & Join explode() Breaks a string into an array str_split()
Splits a string into an array
implode()
Returns a string from the elements of an array
join()
Alias of implode()

7. explode( )
<?php $strW = "HTML, CSS, JavaScript, PHP"; $arrW = explode(", ",$strW); echo "<ul>"; for ($i=0;$i<count($arrW);$i++) echo "<li>$arrW[$i]</li>"; echo "</ul>"; ?>

8. implode( )
<?php $arrW = array("HTML", "CSS", "JavaScript", "PHP"); echo "[" . implode("] [",$arrW) . "]"; ?>

9. ltrim( ), rtrim( ), trim( )
Strips whitespace from both sides of a string
chop()
Alias of rtrim()
rtrim()
Strips whitespace from the right side of a string
ltrim()
Strips whitespace from the left side of a string
<?php
$hw = " Hello World! ";
echo "\"$hw\"<br/>";
echo "ltrim: \"" . ltrim($hw) . "\"<br/>";
echo "rtrim: \"" . rtrim($hw) . "\"<br/>";
echo "trim: \"" . trim($hw) . "\"<br/>";
?>

10. Replace, Convert str_replace()
Replaces some characters in a string (case-sensitive)
str_ireplace()
Replaces some characters in a string (case-insensitive)
substr_replace()
Replaces a part of a string with another string
str_pad()
Pads a string to a new length
str_repeat()
Repeats a string a specified number of times
str_shuffle()
Randomly shuffles all characters in a string
strrev()
Reverses a string
strtolower()
Converts a string to lowercase letters
strtoupper()
Converts a string to uppercase letters
ucfirst()
Converts the first character of a string to uppercase
ucwords()
Converts the first character of each word in a string to uppercase
addslashes()
Returns a string with backslashes in front of predefined characters
stripslashes()
Unquotes a string quoted with addslashes()

11. Substring, Search strlen() Returns the length of a string substr()
Returns a part of a string
strstr()
Finds the first occurrence of a string inside another string (case-sensitive)
strchr()
Finds the first occurrence of a string inside another string (alias of strstr())
stristr()
Finds the first occurrence of a string inside another string (case-insensitive)
strrchr()
Finds the last occurrence of a string inside another string
strpos()
Returns the position of the first occurrence of a string inside another string (case-sensitive)
stripos()
Returns the position of the first occurrence of a string inside another string (case-insensitive)
strrpos()
Finds the position of the last occurrence of a string inside another string (case-sensitive)
strripos()
Finds the position of the last occurrence of a string inside another string (case-insensitive)
strcmp()
Compares two strings (case-sensitive)
strcasecmp()
Compares two strings (case-insensitive)

12. strpos( ) <?php $email = $_GET['mail']; //$_POST['mail']
if ($pos = strpos($ , {
$user = substr($ ,0,$pos);
$server = substr($ , $pos+1);
echo " $ <br/>";
echo "User name: $user<br/>";
echo "Server: $server<br/>"; }
else
echo "<h2>Wrong !</h2>";
?>