2016.12.20.星期二
一、遞歸的含義
1. 遞歸的公式
function 函數($n){
if($n滿足了結束條件){
return 結束值;
}else{
return 規律運算;
}
}
2.用遞歸輸出從1加到100；
function hanshu($n){
if($n==0){
return $n=0;
}else{
return $n+hanshu($n-1);
}
}
echo hanshu(100);
二、用php寫出簡單的計算器代碼：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf8">
<title></title>
</head>
<body>
<?php
if (isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == '+') {
$result=$_POST["num1"] + $_POST["num2"];
}
elseif (isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == '-') {
$result=$_POST["num1"] - $_POST["num2"];
}
elseif (isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == 'x') {
$result=$_POST["num1"]*$_POST["num2"];
}
elseif (isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == '/') {
$result=$_POST["num1"]/$_POST["num2"];
}
?>
<form action="" method="post">
<input type="text" name="num1" value="<？php if(!empty($_POST['num1'])){echo $_POST['num1'];}?>">
<select name="fuhao">
<option value="+" <?php
if(isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == '+')
{
echo "selected";
}
?>>+</option>
<option value="-" <?php
if(isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == '-')
{
echo "selected";
}
?>>-</option>
<option value="x" <?php
if(isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == 'x')
{
echo "selected";
}
?>>x</option>
<option value="/" <?php
if(isset($_POST['fuhao']) && !empty($_POST['fuhao']) &&$_POST['fuhao'] == '/')
{
echo "selected";
}
?>>/</option>
</select>
<input type="text" name="num2" value="<?php if(!empty($_POST['num2'])) {echo $_POST['num2'];}?>">
<input type="submit" value="=">
<span><?php if(isset($_POST['fuhao']) && !empty($_POST['fuhao']))
{
echo $result;
}
?></span>
</form>
</body>
</html>
完成圖：
