php 时间 数组替换

//随机数和时间
//随机数生产器
//echo rand();
//echo "<br>";
//生成某个范围的随机数
//echo rand(0,10);
//echo "<br>";
//获取当前时间戳
//echo time();

//格式化时间
//echo "<br>";
//echo date("y-m-d H:i:s",time());

//echo "<br>";
//echo date("y-m-d H:i:s","472342375273");
//将字符串转换成时间戳
//echo "<br>";
//echo strtotime("2017-09-27 14:41:08");
//echo "<br>";

//字符串函数
//取字符串长度
//$str = "aklfsklsa";
//echo strlen($str);
//echo "<br>";
//比较字符串
$str1="ashjdnmas";
$str2="safd";
//var_dump(strcmp($str2,$str1));

echo "<br>";
//转小写
//strtolower();

//转大写
//strtoupper();

//拆分字符串
//var_dump(explode("b",$str2));

//将数组元素拼接成一个字符串
//echo implode("|",["q","w","e"]);

//替换指定位置的字符串
echo str_replace("as","AS",$str1);
echo "<br>";
echo $str1;
echo "<br>";
echo substr_replace($str1,"xxx","0","3");
echo "<br>";
//截取字符串
echo substr($str1,"1","3");

//正则表达式
$asd =<<<a
skhd2134kjafou2435hdjkao5463jdkfs6243afjdk
a;
//替换
echo preg_replace("/d/","#",$asd);