Web Database Applications with PHP and MySQL, 2nd Edition

Strings

A string of characters is probably the most commonly used data type when developing scripts, and PHP provides a large library of string functions to help transform, manipulate, and otherwise manage strings. We introduced the basics of PHP strings in Chapter 2. In this section, we show you many of the useful PHP string functions.

Length of a String

The length property of a string is determined with the strlen( ) function, which returns the number of eight-bit characters in the subject string:

integer strlen(string subject)

We used strlen( ) earlier in the chapter to compare string lengths. Consider another simple example that prints the length of a 16-character string:

print strlen("This is a String");  // prints 16

Printing and Formatting Strings

In the previous chapter, we presented the basic method for outputting text with echo and print. Earlier in this chapter, we showed you the functions print_r( ) and var_dump( ), which can determine the contents of variables during debugging. PHP provides several other functions that allow more complex and controlled formatting of strings, and we discuss them in this section.

Creating formatted output with sprintf( ) and printf( )

Sometimes, more complex output is required than can be produced with echo or print. For example, a floating-point value such as 3.14159 might need to be truncated to 3.14 in the output. For complex formatting, the sprintf( ) or printf( ) functions are useful:

string sprintf (string format [, mixed args...])