srcmini使用isset()函数
isset()函数是PHP中的内置函数, 它检查是否设置了变量, 并且该变量不是NULL。此函数还检查声明的变量, 数组或数组键是否具有空值, 如果存在, 则isset()返回false, 在所有其他可能情况下返回true。可以使用isset()函数解决此问题。
语法如下：
bool isset( $var, mixed )描述：此函数接受多个参数。该函数的第一个参数是$ var。此参数用于存储变量的值。
程序：
<? php
if(isset($_GET['submit'])) {
$var = $_GET['option1'];
if(isset($var)) {
echo "Option 1 submitted successfully";
}
}
?>
<html lang = "en">
<head>
<title>srcmini Example</title>
<meta charset = "utf-8">
<meta name = "viewport" content = "width=device-width, initial-scale=1">
<link rel = "stylesheet" href =
"https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<style>
.gfg {
font-size:40px;
font-weight:bold;
color:green;
}
body {
text-align:center;
}
</style>
</head>
<body>
<div class = "container">
<div class = "gfg">srcmini</div>
<h2>Form control: checkbox</h2>
<p>The form below contains one checkbox.</p>
<form method = "get">
<div class = "checkbox">
<label><input type = "checkbox" name = "option1"
value = "Option 1">Option 1</label>
<label><button name = "submit" value = 'true'
class = "btn btn-default">SUBMIT</button>
</div>
</form>
</div>
</body>
</html>输出如下：
使用empty()函数
empty()函数是PHP中的内置函数, 用于检查变量是否为空。
语法如下：
bool empty( $var )描述：此函数确定变量是否为空。
例子：
<? php
if(!empty($_GET['submit'])) {
$var = $_GET['option1'];
if(isset($var)){
echo "Option 1 submitted successfully";
}
}
?>
<!DOCTYPE html>
<html lang = "en">
<head>
<title>srcmini Example</title>
<meta charset = "utf-8">
<meta name = "viewport" content = "width=device-width, initial-scale=1">
<link rel = "stylesheet" href =
"https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src = "https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js">
</script>
<style>
.gfg {
font-size:40px;
font-weight:bold;
color:green;
}
body {
text-align:center;
}
</style>
</head>
<body>
<div class = "container">
<div class = "gfg">srcmini</div>
<h2>Form control: checkbox</h2>
<p>The form below contains one checkbox.</p>
<form method = "get">
<div class = "checkbox">
<label><input type = "checkbox" name = "option1"
value = "Option 1">Option 1</label>
<label><button name = "submit" value = "true"
class = "btn btn-default">SUBMIT</button>
</div>
</form>
</div>
</body>
</html>输出如下：
参考：
- http://php.net/manual/en/function.isset.php
- http://php.net/manual/en/function.empty.php
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