php 过滤器实现代码

当难的数据为"1","true","on","yes"时返回true，否则返回false。当设置了FILTER_NULL_ON_FAILURE标志位，则仅在值是"0","false","off","no", 和""是返回false，其它非true值返回null。 FILTER_VALIDATE_EMAIL "validate_email" 验证邮箱 FILTER_VALIDATE_FLOAT "float" decimal FILTER_FLAG_ALLOW_THOUSAND 验证浮点数 FILTER_VALIDATE_INT "int" min_range, max_range FILTER_FLAG_ALLOW_OCTAL, FILTER_FLAG_ALLOW_HEX 验证一个指定范围内的整数值 FILTER_VALIDATE_IP "validate_ip" FILTER_FLAG_IPV4, FILTER_FLAG_IPV6, FILTER_FLAG_NO_PRIV_RANGE, FILTER_FLAG_NO_RES_RANGE 验证IP地址 FILTER_VALIDATE_REGEXP "validate_regexp" regexp 验证一个正则表达式 FILTER_VALIDATE_URL "validate_url" FILTER_FLAG_PATH_REQUIRED, FILTER_FLAG_QUERY_REQUIRED 验证一个URL Sanitizing FILTER_SANITIZE_EMAIL "email" 移除除英文字符，数字以及!#$%&'*+-/=?^_`{|}~@.[]之外的字符。 FILTER_SANITIZE_ENCODED "encoded" FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH URL编码字符串，去除或编码指定字符串。 FILTER_SANITIZE_MAGIC_QUOTES "magic_quotes" 应用 addslashes()函数 FILTER_SANITIZE_NUMBER_FLOAT "number_float" FILTER_FLAG_ALLOW_FRACTION, FILTER_FLAG_ALLOW_THOUSAND, FILTER_FLAG_ALLOW_SCIENTIFIC 移除除数字，+-以及.,eE以外的字符 FILTER_SANITIZE_NUMBER_INT "number_int" 移除除数字以及+-以外的字符 FILTER_SANITIZE_SPECIAL_CHARS "special_chars" FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_HIGH HTML转义字符，'"&><以及 ASCII 值小于 32 的字符。以及其它指定的字符。 FILTER_SANITIZE_STRING "string" FILTER_FLAG_NO_ENCODE_QUOTES, FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH, FILTER_FLAG_ENCODE_AMP 去除标签，或是去除或编码指定的字符。 FILTER_SANITIZE_STRIPPED "stripped" Alias of "string" filter. FILTER_SANITIZE_URL "url" 删除所有字符除字母、数字以及$-_.+!*'(),{}|^~[]`<>#%";/?:@&= FILTER_UNSAFE_RAW "unsafe_raw" FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH, FILTER_FLAG_ENCODE_AMP