PHP截取字符串

substr($row['keyid'],0,3);截取前3个字符串

substr("she is a well-read girl",0);从第0个字符开始截取

substr("she is a well-read girl",4，14);从第4个字符开始连续截取14个字符

substr("she is a well-read girl",-4，4);从倒数第4个字符开始截取4个字符

substr("she is a well-read girl",0，-4);从第1个字符开始截取，截取到倒数第4个字符