PHP string function summary
本篇文章介绍了关于php 字符串函数的总结 ，给大家分享一下，有兴趣的朋友可以看一下
转义字符串：
addslashes — 使用反斜线引用字符串
stripslashes — 反引用一个引用字符串
htmlentities —将字符转换为 HTML 转义字符
html_entity_decode — Convert all HTML entities to their applicable characters
$orig = "I'll \"walk\" the <b>dog</b> now";$a = htmlentities($orig);$b = html_entity_decode($a);echo "用htmlentities转义输出的：".$a; echo "<br/>";echo "<br/>";echo "用html_entity_decode反转义输出的：".$b;
htmlspecialchars— 将特殊字符转换为 HTML 实体
htmlspecialchars_decode— 将特殊的 HTML 实体转换回普通字符
htmlentities()各方面都和htm
lspecialchars()一样， 除了htmlentities()会转换所有具有 HTML 实体的字符，可能导致中文乱码，需要注意encoding参数的添加
get_html_translation_table — 返回使用
htmlspecialchars和htmlentities后的转换表quotemeta — 转义元字符集
分割合并字符串
chunk_split — 将字符串分割成小块
<?php//将 1234567890 转换成 1,234,567,890 每 3 位用逗号隔开的形式。$str = 1234567890;//字符串反转$rstr = strrev($str);$rstr = chunk_split($rstr,3,',');$str = strrev($rstr);//去除左边的','$str = ltrim($str,',');echo $str;
explode —使用一个字符串分割另一个字符串
implode — 将一个一维数组的值转化为字符串
str_split — 将字符串转换为数组
填充、替换字符串
str_pad —使用另一个字符串填充字符串为指定长度
str_repeat — 重复一个字符串
str_replace —子字符串替换
str_ireplace — str_replace 的忽略大小写版本
strtr — 转换指定字符
处理子字符串
substr — 返回字符串的子串
substr_count — 计算字串出现的次数
substr_replace— 替换字符串的子串
查找字符串
strstr — 查找字符串的首次出现
stristr — strstr 函数的忽略大小写版本
strpos — 查找字符串首次出现的位置
stripos —查找字符串首次出现的位置（不区分大小写）
strrpos —计算指定字符串在目标字符串中最后一次出现的位置
strripos —计算指定字符串在目标字符串中最后一次出现的位置（不区分大小写）
去除字符串
ltrim — 删除字符串开头的空白字符（或其他字符）
rtrim — 删除字符串末端的空白字符（或者其他字符）
trim — 去除字符串首尾处的空白字符（或者其他字符）
strip_tags — 从字符串中去除 HTML 和 PHP 标记
转换大小写
lcfirst —使一个字符串的第一个字符小写
ucfirst — 将字符串的首字母转换为大写
strtolower — 将字符串转化为小写
strtoupper — 将字符串转化为大写
ucwords — 将字符串中每个单词的首字母转换为大写
其他转换字符串
nl2br — 在字符串所有新行之前插入HTML 换行标记
number_format — 以千位分隔符方式格式化一个数字
$number = 123456.56;//默认千位符用',' 小数点用'.'$format_number = number_format($number,1);echo $format_number;
strrev — 反转字符串
ip2long — 将 IPV4 的字符串互联网协议转换成长整型数字
long2ip — 将长整型转化为字符串形式带点的互联网标准格式地址（IPV4）
加密字符串
crypt — 单向字符串散列
<?phpif (CRYPT_STD_DES == 1) { echo 'Standard DES: ' . crypt('rasmuslerdorf', 'rl') . "\n";
}if (CRYPT_EXT_DES == 1) { echo 'Extended DES: ' . crypt('rasmuslerdorf', '_J9..rasm') . "\n";
}if (CRYPT_MD5 == 1) { echo 'MD5: ' . crypt('rasmuslerdorf', '$1$rasmusle$') . "\n";
}if (CRYPT_BLOWFISH == 1) { echo 'Blowfish: ' . crypt('rasmuslerdorf', '$2a$07$usesomesillystringforsalt$') . "\n";
}if (CRYPT_SHA256 == 1) { echo 'SHA-256: ' . crypt('rasmuslerdorf', '$5$rounds=5000$usesomesillystringforsalt$') . "\n";
}if (CRYPT_SHA512 == 1) { echo 'SHA-512: ' . crypt('rasmuslerdorf', '$6$rounds=5000$usesomesillystringforsalt$') . "\n";
}md5 — 计算字符串的 MD5 散列值
sha1 — 计算字符串的 sha1 散列值
输出字符串
echo — 输出一个或多个字符串
print — 输出字符串
printf — 输出格式化字符串
获取字符串信息
chr — 返回 ASCII 码值指定的字符
ord — 返回字符的 ASCII 码值
parse_str — 将字符串解析成多个变量
<?php$str = "first=value&arr[]=foo+bar&arr[]=baz";// 推荐用法parse_str($str, $output);echo $output['first']; // valueecho "<br/>";echo $output['arr'][0]; // foo barecho "<br/>";echo $output['arr'][1]; // baz
strlen — 获取字符串长度
比较字符串
strcmp — 二进制安全字符串比较
strcasecmp — 二进制安全比较字符串（不区分大小写）
strnatcmp — 使用自然排序算法比较字符串
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