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Handling Strings and Arrays in PHP

In PHP, two types of data (strings and arrays) warrant special attention and a more complete explanation. This chapter details how and why these special data types are employed in PHP 5 with copious examples to get you started using these in your code.
This chapter is from the book

This chapter is from the book

Two data types merit some special attention—strings and arrays. We've already seen strings at work, including single- and double-quoted strings (recall also that double-quoted strings allow variable interpolation). PHP also comes packed with more string power, and we're going to dig into that in this chapter—tons of functions are built into PHP that work with strings, from sorting strings to searching them, trimming extra spaces off of them, and getting their lengths. We'll get a handle on those functions in this chapter.

Besides strings, we're also going to get a handle on arrays in this chapter. We've seen how to store data in simple variables, but there's more to the story here. Arrays can hold multiple data items, assigning each one a numeric or text index (also called a key). For example, if you want to store some student test scores, you can store them in an array, and then you can access each score in the array via a numeric index. That's great as far as computers are concerned because you can work through all the elements in an array simply by steadily incrementing that index, as you might do with a loop. In that way, you can use your computer to iterate over all the elements in an array in order to print them out or find their average value, for example.

Arrays represent the first time we're associating data items together. Up to this point, we've only worked with simple variables, but working with arrays is fundamental to PHP for such tasks as reading the data that users enter in web pages. We'll get the details on strings and arrays in this chapter, and I'll start with the string functions.

Listing of String Functions

PHP has plenty of built-in string functions. Table 3-1 lists a selection of them.

Table 3-1. The String Functions




Returns a specific character, given its ASCII code


Splits a string into smaller chunks


Supports one-way string encryption (hashing)


Displays one or more strings


Splits a string on a substring


Converts all HTML entities to their applicable characters


Converts all applicable characters to HTML entities


Converts special characters to HTML entities


Joins array elements with a string


Strips whitespace from the beginning of a string


Formats a number with grouped thousand separators


Returns the ASCII value of character


Parses the string into variables


Displays a string


Displays a formatted string


Strips whitespace from the end of a string


Sets locale information


Calculates the similarity between two strings


Returns a formatted string


Parses input from a string according to a format


Case-insensitive version of the str_replace function.


Pads a string with another string


Repeats a string


Replaces all occurrences of the search string with the replacement string


Shuffles a string randomly


Converts a string to an array


Returns information about words used in a string


Binary case-insensitive string comparison


Alias of the strstr function


Binary-safe string comparison


Strips HTML and PHP tags from a string


Finds position of first occurrence of a case-insensitive string


Case-insensitive version of the strstr function


Gets a string's length


Case-insensitive string comparisons


String comparisons using a "natural order" algorithm


Binary case-insensitive string comparison of the first n characters


Binary-safe string comparison of the first n characters


Finds position of first occurrence of a string


Finds the last occurrence of a character in a string


Reverses a string


Finds the position of last occurrence of a case-insensitive string


Finds the position of last occurrence of a char in a string


Finds the length of initial segment matching mask


Finds the first occurrence of a string


Converts a string to lowercase


Converts a string to uppercase


Translates certain characters


Binary-safe (optionally case-insensitive) comparison of two strings from an offset


Counts the number of substring occurrences


Replaces text within part of a string


Returns part of a string


Strips whitespace from the beginning and end of a string

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