记忆表
几个简单的例子(JavaScript)
1. + 的用法
var pattern = /ab+g/;
| 串 | 结果 |
| "dfeoabg" | "abg" |
| "dfeoabfg" | null |
| "dfeoabbg" | "abbg" |
| "dfeoab" | null |
2. ？ 的用法
var pattern = /ab?g/;
| 串 | 结果 |
| "dfeoag" | "ag" |
| "dfeoabg" | "abg" |
| "dfeoabbg" | null |
| "dfeobg" | null |
3. (?:) 的用法
var text = "mom and dad and baby";
| 模式 | 结果 |
| /mom ( and dad ( and baby))/ | ["mom and dad and baby", " and dad and baby", " and baby", index: 0, input: "mom and dad and baby"] |
| /mom ( and dad (?: and baby))/ | ["mom and dad and baby", " and dad and baby", index: 0, input: "mom and dad and baby"] |
| /mom(?: and dad( and baby))/ | ["mom and dad and baby", " and baby", index: 0, input: "mom and dad and baby"] |
对于正则表达式 ( and baby) ，() 里的内容被捕获，反向引用时可以用上
而 (?: and baby) 可以简单理解成 ?: 关闭了圆括号的捕获能力，只用其来分组，所以不会占用捕获变量，也不能使用反向引用。
关于捕获组与反向引用可参见：http://blog.csdn.net/lxcnn/article/details/4146148
时间： 2024-08-09 21:59:37