What you will learn
- Run a PHP file from the command line and understand the role of the PHP interpreter.
- Write output with echo and recognize PHP tags and statement terminators.
- Distinguish syntax errors, runtime problems, and logic errors.
- Read an error message before changing code.
The code from this chapter
Type these programs yourself. The predictions below are the exercises; the explanations are in the book.
1.1 How PHP Runs
Type this into a file, predict the output, then run it.
<?php
echo "PHP is running." . PHP_EOL;1.2 Statements and Output
Type this into a file, predict the output, then run it.
<?php
// A comment explains why, not what.
$score = 10;
$Score = 20; # a different variable
echo "Two values: ", $score, PHP_EOL;
echo $Score . PHP_EOL;1.3 Three Kinds of Problems
Type this into a file, predict the output, then run it.
<?php
$total = 10;
$count = 0;
echo $total / $count;Type this one as well, and predict it before you run it.
<?php
$width = 7;
$height = 3;
$area = $width + $height;
echo "Area: " . $area . PHP_EOL;TPRM Lab 1.1: Hello from PHP
Type this into a file, predict the output, then run it.
<?php
echo "Hello from PHP!\n";
echo "I am learning by running code.\n";TPRM Lab 1.2: Calculate Before You Print
Type this into a file, predict the output, then run it.
<?php
$width = 7;
$height = 3;
$area = $width * $height;
echo "Area: " . $area . "\n";