Core PHP Programming: Using PHP to Build Dynamic Web Sites

The while Statement

The simplest of loops is the while statement. When first reached, the expression is evaluated. If false, the code block is skipped. If true, the block is executed and then control returns to the top where, again, the expression is evaluated. Figure 3-4 shows the structure of a while statement.

Figure 3-4. The while statement.

A while loop is useful when you aren't sure exactly how many times you will need to iterate through the code—for example, when reading lines from a file or fetching rows from a database query. For the sake of a simple demonstration, let's examine some code that prints the days of the week between now ...