Page 116 - Beginning PHP 5.3

Part II: Learning the Language
Another useful related function is str_word_count() , which returns the number of words in a string.
For example:
echo str_word_count( “Hello, world!” ); // Displays 2

Accessing Characters within a String

You might be wondering how you can access the individual characters of a string. PHP makes this easy
for you. To access a character at a particular position, or index , within a string, use:
$character = $string[index];

In other words, you place the index between square brackets after the string variable name. String
indices start from 0 , so the first character in the string has an index of 0 , the second has an index of 1 ,
and so on. You can both read and change characters this way. Here are some examples:

$myString = “Hello, world!”;
echo $myString[0] . “ < br / > ”; // Displays ‘H’
echo $myString[7] . “ < br / > ”; // Displays ‘w’
$myString[12] = ‘?’;
echo $myString . “ < br / > ”; // Displays ‘Hello, world?’

If you need to extract a sequence of characters from a string, you can use PHP ’ s substr() function. This
function takes the following parameters:

❑ The string to extract the characters from
❑ The position to start extracting the characters. If you use a negative number, substr() counts
backward from the end of the string
❑ The number of characters to extract. If you use a negative number, substr() misses that many
characters from the end of the string instead. This parameter is optional; if left out, substr()
extracts from the start position to the end of the string
Here are a few examples that show how to use substr() :
$myString = “Hello, world!”;
echo substr( $myString, 0, 5 ) . “ < br/ > ”; // Displays ‘Hello’
echo substr( $myString, 7 ) . “ < br/ > ”; // Displays ‘world!’
echo substr( $myString, -1 ) . “ < br/ > ”; // Displays ‘!’

echo substr( $myString, -5, -1 ) . “ < br/ > ”; // Displays ‘orld’

You can ’ t modify characters within strings using substr() . If you need to change characters within a
string, use substr_replace() instead. This function is described later in the chapter.
Searching Strings

Often it ’ s useful to know whether one string of text is contained within another. PHP gives you several
string functions that let you search for one string inside another:

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