PHP in_array

1.函数的作用：判读一个元素是否在一个数组存在

2.函数的参数：

　　@param mixed $needle

　　@param array $array

3. if it’s ok to use isset() function ,then better to use the isset() function instead of in_array() function.

4.

例子一：

<?php
$arr = [
    '1314LoveZhangbiyu',
];
if(in_array(1314,$arr)){
    echo '1314';
    echo "
";
}

if(in_array('1314',$arr)){
    echo 'string 1314 is in!';
    echo "
";
}else{
    echo 'string 1314 is not in!';
    echo "
";
}

 例子二：

<?php
$a = array('0' => 'Opt 1', '1' => 'Opt 2', '2' => 'Opt 3');
$v = 'sql injection';
var_dump(in_array($v, array_keys($a)));