## 验证

示例 #1 使用 filter_var() 验证电子邮件地址

`<?php
$email_a = 'joe@example.com';
$email_b = 'bogus';
if (filter_var($email_a, FILTER_VALIDATE_EMAIL)) {
echo "Email address '$email_a' is considered valid.\n";
}
if (filter_var($email_b, FILTER_VALIDATE_EMAIL)) {
echo "Email address '$email_b' is considered valid.\n";
} else {
echo "Email address '$email_b' is considered invalid.\n";
}
?>`

以上示例会输出：

    Email address 'joe@example.com' is considered valid.
    Email address 'bogus' is considered invalid.

示例 #2 使用 filter_var() 验证 IP 地址

`<?php
$ip_a = '127.0.0.1';
$ip_b = '42.42';
if (filter_var($ip_a, FILTER_VALIDATE_IP)) {
echo "IP address '$ip_a' is considered valid.";
}
if (filter_var($ip_b, FILTER_VALIDATE_IP)) {
echo "IP address '$ip_b' is considered valid.";
}
?>`

以上示例会输出：

    IP address '127.0.0.1' is considered valid.

示例 #3 传递选项到 filter_var()

`<?php
$int_a = '1';
$int_b = '-1';
$int_c = '4';
$options = array(
'options' => array(
'min_range' => 0,
'max_range' => 3,
)
);
if (filter_var($int_a, FILTER_VALIDATE_INT, $options) !== FALSE) {
echo "Integer A '$int_a' is considered valid (between 0 and 3).\n";
}
if (filter_var($int_b, FILTER_VALIDATE_INT, $options) !== FALSE) {
echo "Integer B '$int_b' is considered valid (between 0 and 3).\n";
}
if (filter_var($int_c, FILTER_VALIDATE_INT, $options) !== FALSE) {
echo "Integer C '$int_c' is considered valid (between 0 and 3).\n";
}
$options['options']['default'] = 1;
if (($int_c = filter_var($int_c, FILTER_VALIDATE_INT, $options)) !== FALSE) {
echo "Integer C '$int_c' is considered valid (between 0 and 3).";
}
?>`

以上示例会输出：

    Integer A '1' is considered valid (between 0 and 3).
    Integer C '1' is considered valid (between 0 and 3).

`↑` and `↓` to navigate • `Enter` to select • `Esc` to close • `/` to open