Learning PHP and MySQL
Thursday, August 03, 2006
Example 04-03 Lefthand expressions
<?php
3 = $locations; // bad - a value can not be assign to the literal 3
$a + $b = $c; //bad - the expression on the left isn't one variable
$c = $a + $b; //OK
$stores = "Becker"." "."Furniture"; // OK
?>
Posted by krautgrrl on 08/03 at 08:08 AM
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Chapter 4 Code • (0) Comments • (29) Trackbacks • Permalink
Example 04-04 Order of precedence
2 + 4 - 5 == 1;
4 - 5 + 2 == 1;
4 * 5 / 2 == 10;
5 / 2 * 4 == 10;
2 + 4 - 5 == 1;
4 - 5 + 2 == 1;
4 * 5 / 2 == 10;
5 / 2 * 4 == 10;
Posted by krautgrrl on 08/03 at 08:09 AM
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Chapter 4 Code • (0) Comments • (74) Trackbacks • Permalink
Example 04-05 The multiplication is done last because of the override
<?php
echo 2 * 3 + 4 + 1;
echo 2 * (3 + 4 + 1);
?>
Posted by krautgrrl on 08/03 at 08:10 AM
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Chapter 4 Code • (0) Comments • (412) Trackbacks • Permalink
Example 04-06 Else and if statements
<?php
if ($username == "Admin"){
echo ('Welcome to the admin page.');
}
else {
echo ('Welcome to the user page.');
}
?>
Posted by krautgrrl on 08/03 at 08:10 AM
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Chapter 4 Code • (0) Comments • (102) Trackbacks • Permalink
Example 04-07 Checking multiple conditions
<?php
if ($username == "Admin"){
echo ('Welcome to the admin page.');
}
elseif ($username == "Guest"){
echo ('Please take a look around.');
}
else {
echo ("Welcome back, $username.");
}
?>
Posted by krautgrrl on 08/03 at 08:11 AM
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Chapter 4 Code • (0) Comments • (495) Trackbacks • Permalink
Example 04-08 Using the ? operator to create a message
<?php
$logged_in = TRUE;
$user = "Admin";
$banner = ($logged_in==TRUE)?"Welcome back $user!":"Please login.";
echo "$banner";
?>
Posted by krautgrrl on 08/03 at 08:12 AM
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Chapter 4 Code • (1) Comments • (352) Trackbacks • Permalink
Example 04-09 Using if to test for multiple values
<?php
if ($action == "ADD") {
echo "Perform actions for adding.";
echo "As many statements as you like can be in each block.";
}
elseif ($action == "MODIFY") {
echo "Perform actions for modifying.";
}
elseif ($action == "DELETE") {
echo "Perform actions for deleting.";
}
?>
Example 04-10 Using switch to test for multiple values
<?php
switch ($action) {
case "ADD":
echo "Perform actions for adding.";
echo "As many statements as you like can be in each block.";
break;
case "MODIFY":
echo "Perform actions for modifying.";
break;
case "DELETE":
echo "Perform actions for deleting.";
break;
}
?>
Posted by krautgrrl on 08/03 at 08:13 AM
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Chapter 4 Code • (0) Comments • (286) Trackbacks • Permalink
Example 04-11 What happens when there are no break keywords
<?php
$action=”ASSEMBLE ORDER”;
switch ($action) {
case "ASSEMBLE ORDER":
echo "Perform actions for order assembly.<br>";
case "PACKAGE":
echo "Perform actions for packing.<br>";
case "SHIP":
echo "Perform actions for shipping.<br>";
?>
Posted by krautgrrl on 08/03 at 08:13 AM
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Chapter 4 Code • (0) Comments • (382) Trackbacks • Permalink
Example 04-12 Using the DEFAULT: statement to generate an error
<?php
switch ($action) {
case "ADD":
echo "Perform actions for adding.";
break;
case "MODIFY":
echo "Perform actions for modifying.";
break;
case "DELETE":
echo "Perform actions for deleting.";
break;
default:
echo "Error: Action must be either ADD, MODIFY, or DELETE.";
}
?>
Example 04-13 Using endswitch to end the switch definition
<?php
switch ($action):
case "ADD":
echo "Perform actions for adding.";
break;
case "MODIFY":
echo "Perform actions for modifying.";
break;
case "DELETE":
echo "Perform actions for deleting.";
break;
default:
echo "Error: Action must be either ADD, MODIFY, or DELETE.";
endswitch;
?>
Example 04-14 A sample while loop that counts to 10
<?php
$num = 1;
while ($num <= 10){
print "Number is $num<br />\n";
$num++;
}
print 'Done.';
?>
Posted by krautgrrl on 08/03 at 08:15 AM
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Chapter 4 Code • (0) Comments • (888) Trackbacks • Permalink
Example 04-15 Counting to 10 with do… while
<?php
$num = 1;
do {
echo "Number is ".$num."<br />";
$num++;
} while ($num <= 10);
echo "Done.";
?>
Example 04-16 Using break to avoid division by zero
<?php
$counter = -3;
for (; $counter < 10; $counter++){
// Check for division by zero
if ($counter == 0){
echo "Stopping to avoid division by zero.";
break;
}
echo "100/$counter<br/>";
}
?>
Example 04-17 Using continue instead of break
<?php
$counter =- 3;
for (; $counter < 10; $counter++){
// Check for division by zero
if ($counter == 0){
echo "Skipping to avoid division by zero.<br />";
continue;
}
echo "100/$counter<br />";
}
?>
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