Basic PHP String Operations

Explains some basic concepts of PHP strings. Find out how to join strings together, get the length of a string, and access characters within a string.

Now that you know how to create strings in PHP, it's time to try out some basic string operations. In this tutorial you learn how to:

  • Join strings together
  • Find out the length of a string, and
  • Read and change individual characters within a string.

Joining strings

To join 2 or more strings together to make 1 long string, use the concatenation operator, which is a . (dot). For example, to join 2 strings you could use:

$string1 = 'Hello, ';
$string2 = 'there!';
$string3 = $string1 . $string2;
echo $string3; // Displays "Hello, there!" 

To join 3 strings you might write:

$string1 = 'Hello,';
$string2 = ' ';
$string3 = 'there!';
$string4 = $string1 . $string2 . $string3;
echo $string4; // Displays "Hello, there!" 

Getting the length of a string

You can use PHP's strlen() function to retrieve the number of characters in a string:

$myString = 'Hello, there!';
echo strlen( $myString ); // Displays "13" 

If you want to find out the number of words in a string, you can use str_word_count():

$myString = 'Hello, there!';
echo str_word_count( $myString ); // Displays "2"

Accessing characters within a string

To access a character in a string, write the string variable name followed by the character position, or index, in square brackets:

$myString = 'Hello, there!';
echo $myString[7];  // Displays "t"

String indices start from zero. The first character in a string has an index of 0, the second has an index of 1, and so on.

You can change characters in a string using the same technique:

$myString = 'Hello, there!';
$myString[12] = '?';
echo $myString;  // Displays "Hello, there?"

If you want to read a sequence of characters from a string, use PHP's substr() function. This takes the following arguments:

  • The string.
  • The position to start extracting characters. Use a negative number to count backwards from the end of the string.
  • The number of characters to extract (optional). Miss out this argument to extract from the start position to the end of the string. You can also supply a negative number to miss out that many characters from the end of the string.

Here are some substr() examples:

$myString = 'Hello, there!';
echo substr( $myString, 7 ) . "<br />";       // Displays "there!"
echo substr( $myString, 0, 5 ) . "<br />";    // Displays "Hello"
echo substr( $myString, -4 ) . "<br />";      // Displays "ere!"
echo substr( $myString, -6, -1 ) . "<br />";  // Displays "there"

You can't use substr() to change characters within strings; however you can do this with PHP's substr_replace() function.

You now know how to carry out basic operations on PHP strings. You've looked at joining strings together; how to find out the length of a string; and how to work with individual characters within a string. Happy coding!

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