$str1 = substr($str,5);
echo "从第5个字符开始取至最后：".$str1."
";
$str2 = substr($str,9,4);
echo "从第9个字符开始取4个字符：".$str2."
";
$str3 = substr($str,-5);
echo "取倒数5个字符：".$str3."
";
$str4 = substr($str,-8,4);
echo "从倒数第8个字符开始向后取4个字符：".$str4."
";
$str5 = substr($str,-8,-2);
echo "从倒数第8个字符开始取到倒数第2个字符：".$str5."
echo "从第5个字符开始取至最后：".$str1."
";
$str2 = substr($str,9,4);
echo "从第9个字符开始取4个字符：".$str2."
";
$str3 = substr($str,-5);
echo "取倒数5个字符：".$str3."
";
$str4 = substr($str,-8,4);
echo "从倒数第8个字符开始向后取4个字符：".$str4."
";
$str5 = substr($str,-8,-2);
echo "从倒数第8个字符开始取到倒数第2个字符：".$str5."
";
为防止中文乱码，用下面方法
mb_substr($str, 0, 7, 'utf-8');