PHP5&MySQL 程式設計

PHP5&MySQL程式設計 第3章控制結構

3-1　認識控制結構 • 判斷結構 (decision structures) • if (if…、if…else…、if…elseif…) • switch • 迴圈結構 (loop structures) • for • foreach • while • do…while

3-2if 3-2-1if：如果…就…(單向選擇) if (condition) statement; if (condition) { statement1; statement2; … statementN; }

\ch03\prac03-1.php <HTML> <HEAD> <TITLE> if... </TITLE> </HEAD> <BODY> <?php $a = 20; $b = 10; if ($a > $b) echo '$a比$b大'; ?> </BODY> </HTML>

3-2-2if…else…：如果…就…否則…(雙向選擇) if (condition) { statements1; } else { statements2; }

\ch03\prac03-2.php <HTML> <HEAD> <TITLE>if...else...</TITLE> </HEAD> <BODY> <?php $score = 59; if ($score > 60) echo '及格！'; else echo '不及格！'; ?> </BODY> </HTML>

3-2-3if…elseif…：「如果…就….否則如果…就…否則…」(多向選擇) if (condition1) { statements1 } elseif (condition2) { statements2 } elseif (condition3) { statements3 } … else { statementsN+1 }

\ch03\prac03-3.php <BODY> <?php $score = 85; if ($score >= 90) echo '優等！'; elseif ($score < 90 && $score >= 80) echo '甲等！'; elseif ($score < 80 && $score >= 70) echo '乙等！'; elseif ($score < 70 && $score >= 60) echo '丙等！'; else echo '不及格！'; ?> </BODY>

3-2-4if的替代語法 \ch03\prac03-4.php <?php $a = 20; $b = 20; if ($a > $b){ echo '$a比$b大'; echo '!'; }elseif ($a < $b){ echo '$a比$b小'; echo '!'; }else{ echo '$a等於$b'; echo '!'; } ?>

<?php $a = 20; $b = 20; if ($a > $b): echo '$a比$b大'; echo '!'; elseif ($a < $b): echo '$a比$b小'; echo '!'; else: echo '$a等於$b'; echo '!'; endif ?>

3-3switch switch(expression) { case value1: statements1; break; case value2: statements2; break; … default: statementsN+1 }

<?php $number = 3; switch($number) { case 1: echo 'ONE'; break; case 2: echo 'TWO'; break; case 3: echo 'THREE'; break; case 4: echo 'FOUR'; break; case 5: echo 'FIVE'; break; default: echo '數值超過範圍！'; } ?>

<?php $number = 3; if ($number == 1) echo 'ONE'; elseif ($number == 2) echo 'TWO'; elseif ($number == 3) echo 'THREE'; elseif ($number == 4) echo 'FOUR'; elseif ($number == 5) echo 'FIVE'; else echo '數值超過範圍！'; ?>

3-4for (計數迴圈) for (initializers; expression; iterators) { statements [break;] statements }

\ch03\prac03-8a.php <HTML> <HEAD> <TITLE>for</TITLE> </HEAD> <BODY> <?php for ($i = 1; $i <= 10; $i++) echo $i.' '; ?> </BODY> </HTML>

\ch03\prac03-8b.php <HTML> <HEAD> <TITLE>for</TITLE> </HEAD> <BODY> <?php for ($i = 1; ; $i++){ if ($i > 10) break; echo $i.' '; } ?> </BODY> </HTML>

\ch03\prac03-8c.php <HTML> <HEAD> <TITLE>for</TITLE> </HEAD> <BODY> <?php for (;;){ ++$i; if ($i > 10) break; echo $i.' '; } ?> </BODY> </HTML>

break敘述的妙用 \ch03\prac03-12.php 01:<HTML> 02: <HEAD> 03: <TITLE>for</TITLE> 04: </HEAD> 05: <BODY> 06: <?php 07: $result = 1; 08: for ($i = 1; $i <= 10; $i++){ 09: if ($i > 6) break; 10: $result = $result * $i; 11: } 12: echo $result; 13: ?> 14: </BODY> 15:</HTML>

3-5　條件式迴圈 3-5-1while while(condition) { statements [break;] statements }

\ch03\prac03-13.php <HTML> <HEAD> <TITLE>while</TITLE> </HEAD> <BODY> <?php while ($i < 10) echo ++$i.' '; ?> </BODY> </HTML>

3-5-2do…while do { statements [break;] statements }while(condition);

\ch03\prac03-14.php <HTML> <HEAD> <TITLE>do...while</TITLE> </HEAD> <BODY> <?php do echo ++$i.' '; while ($i < 10) ?> </BODY> </HTML>

3-5-3break與continue敘述 \ch03\prac03-15.php <HTML> <BODY> <?php for ($i = 1; $i <= 15; $i++) { if ($i <= 10) continue; echo $i.' '; } ?> </BODY> </HTML>

3-5-4exit()/die() 函式 • 例如： exit('檔案開啟失敗，程式終止執行！');

3-6foreach foreach (array_name as $value){ statements [break;] statements } foreach (array_name as $key => $value) { statements [break;] statements }

\ch03\prac03-16.php 01:<HTML> 02: <HEAD> 03: <TITLE>foreach</TITLE> 04: </HEAD> 05: <BODY> 06: <?php 07: $city = array('東京', '台北', '紐約'); 08: foreach ($city as $value) 09: echo $value.' '; 10: ?> 11: </BODY> 12:</HTML>

\ch03\prac03-17.php 01:<HTML> 02: <HEAD> 03: <TITLE>foreach</TITLE> 04: </HEAD> 05: <BODY> 06: <?php 07: $city = array('Japan' => '東京', 'Taiwan' => '台北', 'USA' => '紐約'); 08: foreach ($city as $key => $value) 09: echo '鍵：'.$key.'；值：'.$value.' '; 10: ?> 11: </BODY> 12:</HTML>

PHP5&MySQL 程式設計