php字符的替换，截取，指定查找

<?php/** * Created by 郭鹏. * User: msi * Date: 2017/9/27 * Time: 14:17 */

//随机数生成器echo rand();echo  "<br>";//生成某个范围随机数echo rand(0,10);echo  "<br>";//获取当前时间戳echo time();echo  "<br>";//格式化显示时间echo  "<br>";echo date("Y-m-d H:i:s",time());echo  "<br>";echo date("Y-m-d H:i:s","1506494976");//字符串转换成时间戳echo "<br>";echo strtotime("2017-09-27 14:37:39");echo  "<br>";

//取字符串的长度$str1 = "abcdefg";$str2 = "abc";//echo strlen();echo  "<br>";//比较两个字符串，美国信息交换标准代码；var_dump(strcmp($str1,$str2));//转小写echo  "<br>";strtolower($str2);//转大写//strtoupper();//拆分字符串echo  "<br>";var_dump(explode("b",$str2));

//将数组元素拼接成一个字符串echo  "<br>";echo implode("|",["a","b","c"]);

//替换替换echo  "<br>";//这里拿到是返回值，所以要用到echo输出一下；echo str_replace("cd","CD",$str1);echo "<br>";echo $str1;

//替换指定位置的字符串echo "<br>";echo substr_replace($str1,"xxx",0,3);

//截取字符串echo "<br>";echo substr($str1,1,3);

//正则表达式$str =<<<A456abcdefghijklmn123A;echo "<br>";//上述所有字符的数字替换成#echo preg_replace("/\d/","#",$str);