substr() 函数返回字符串的一部分。
语法：substr(string,start,length)。
注释：如果 start 是负数且 length 小于等于 start，则 length 为 0。
| 1 | <?php |
| 2 | $rest = substr("abcdef", -1); // returns "f" |
| 3 | echo $rest.'<br />'; |
| 4 | $rest = substr("abcdef", -2); // returns "ef" |
| 5 | echo $rest.'<br />'; |
| 6 | $rest = substr("abcdef", -3, 1); // returns "d" |
| 7 | echo $rest.'<br />'; |
| 8 | ?> |
程序运行结果：
| 1 | f |
| 2 | ef |
| 3 | d |
就是从start位置开始，若length为负值的话，就从字符串的末尾开始数。substr("abcdef", 2, -1)的话，就是从c开始，然后-1说明截取到e，就是要截取cde。
| 01 | <?php |
| 02 | $rest = substr("abcdef", 0, -1); // returns "abcde" |
| 03 | echo $rest.'<br />'; |
| 04 | $rest = substr("abcdef", 2, -1); // returns "cde" |
| 05 | echo $rest.'<br />'; |
| 06 | $rest = substr("abcdef", 4, -4); // returns "" |
| 07 | echo $rest.'<br />'; |
| 08 | $rest = substr("abcdef", -3, -1); // returns "de" |
| 09 | echo $rest.'<br />'; |
| 10 | ?> |
程序运行结果：
| 1 | abcde |
| 2 | cde |
| 3 | de |
| 01 | <?php |
| 02 | echo substr('abcdef', 1); // bcdef |
| 03 | echo '<br />'; |
| 04 | echo substr('abcdef', 1, 3); // bcd |
| 05 | echo '<br />'; |
| 06 | echo substr('abcdef', 0, 4); // abcd |
| 07 | echo '<br />'; |
| 08 | echo substr('abcdef', 0, 8); // abcdef |
| 09 | echo '<br />'; |
| 10 | echo substr('abcdef', -1, 1); // f |
| 11 | echo '<br />'; |
| 12 | // Accessing single characters in a string |
| 13 | // can also be achieved using "square brackets" |
| 14 | $string = 'abcdef'; |
| 15 | echo $string[0]; // a |
| 16 | echo '<br />'; |
| 17 | echo $string[3]; // d |
| 18 | echo '<br />'; |
| 19 | echo $string[strlen($string)-1]; // f |
| 20 | echo '<br />'; |
| 21 | ?> |
程序运行结果：
| 1 | bcdef |
| 2 | bcd |
| 3 | abcd |
| 4 | abcdef |
| 5 | f |
| 6 | a |
| 7 | d |
| 8 | f |
| 01 | <?php |
| 02 | //removes string from the end of other |
| 03 | function removeFromEnd($string, $stringToRemove) |
| 04 | { |
| 05 | // 获得需要移除的字符串的长度 |
| 06 | $stringToRemoveLen = strlen($stringToRemove); |
| 07 | // 获得原始字符串的长度 |
| 08 | $stringLen = strlen($string); |
| 09 |
| 10 | // 计算出需要保留字符串的长度 |
| 11 | $pos = $stringLen - $stringToRemoveLen; |
| 12 |
| 13 | $out = substr($string, 0, $pos); |
| 14 | return $out; |
| 15 | } |
| 16 | $string = 'nowamagic.jpg.jpg'; |
| 17 | $result = removeFromEnd($string, '.jpg'); |
| 18 | echo $result; |
| 19 | ?> |
程序运行结果：
| 1 | nowamagic.jpg |
| 01 | <?php |
| 02 | $file = "Hellothisfilehasmorethan30charactersandthisfayl.exe"; |
| 03 | function funclongwords($file) |
| 04 | { |
| 05 | if (strlen($file) > 30) |
| 06 | { |
| 07 | $vartypesf = strrchr($file,"."); |
| 08 | // 获取字符创总长度 |
| 09 | $vartypesf_len = strlen($vartypesf); |
| 10 | // 截取左边15个字符 |
| 11 | $word_l_w = substr($file,0,15); |
| 12 | // 截取右边15个字符 |
| 13 | $word_r_w = substr($file,-15); |
| 14 | $word_r_a = substr($word_r_w,0,-$vartypesf_len); |
| 15 | return $word_l_w."...".$word_r_a.$vartypesf; |
| 16 | } |
| 17 | else |
| 18 | return $file; |
| 19 | } |
| 20 | // RETURN: Hellothisfileha...andthisfayl.exe |
| 21 | $result = funclongwords($file); |
| 22 | echo $result; |
| 23 | ?> |
程序运行结果：
| 1 | Hellothisfileha...andthisfayl.exe |
很多时候我们需要显示固定的字数，多出的字数用省略号代替。
| 01 | <?php |
| 02 | $text = 'welcome to nowamagic, I hope you can find something you wanted.'; |
| 03 | $result = textLimit($text, 30); |
| 04 | echo $result; |
| 05 | function textLimit($string, $length, $replacer = '...') |
| 06 | { |
| 07 | if(strlen($string) > $length) |
| 08 | return (preg_match('/^(.*)/W.*$/', substr($string, 0, $length+1),$matches) ? $matches[1] : substr($string, 0, $length)) . $replacer; |
| 09 |
| 10 | return $string; |
| 11 | } |
| 12 | ?> |
程序运行结果：
| 1 | welcome to nowamagic, I hope... |
有时候我们需要格式化字符串，比如电话号码。
| 01 | <?php |
| 02 | function str_format_number($String, $Format) |
| 03 | { |
| 04 | if ($Format == '') return $String; |
| 05 | if ($String == '') return $String; |
| 06 | $Result = ''; |
| 07 | $FormatPos = 0; |
| 08 | $StringPos = 0; |
| 09 | while ((strlen($Format) - 1) >= $FormatPos) |
| 10 | { |
| 11 | //If its a number => stores it |
| 12 | if (is_numeric(substr($Format, $FormatPos, 1))) |
| 13 | { |
| 14 | $Result .= substr($String, $StringPos, 1); |
| 15 | $StringPos++; |
| 16 | //If it is not a number => stores the caracter |
| 17 | } |
| 18 | else |
| 19 | { |
| 20 | $Result .= substr($Format, $FormatPos, 1); |
| 21 | } |
| 22 | //Next caracter at the mask. |
| 23 | $FormatPos++; |
| 24 | } |
| 25 | return $Result; |
| 26 | } |
| 27 | // For phone numbers at Buenos Aires, Argentina |
| 28 | // Example 1: |
| 29 | $String = "8607562337788"; |
| 30 | $Format = "+00 0000 0000000"; |
| 31 | echo str_format_number($String, $Format); |
| 32 | echo '<br />'; |
| 33 | // Example 2: |
| 34 | $String = "8607562337788"; |
| 35 | $Format = "+00 0000 00.0000000"; |
| 36 | echo str_format_number($String, $Format); |
| 37 | echo '<br />'; |
| 38 | // Example 3: |
| 39 | $String = "8607562337788"; |
| 40 | $Format = "+00 0000 00.000 a"; |
| 41 | echo str_format_number($String, $Format); |
| 42 | echo '<br />'; |
| 43 | ?> |
程序运行结果：
| 1 | +86 0756 2337788 |
| 2 | +86 0756 23.37788 |
| 3 | +86 0756 23.377 a |
新闻热点
疑难解答
