如何找到文本中匹配的单词索引？

Question

我正在提取在this regex中匹配的单词的索引。它使用正则表达式匹配文本中的所有必需单词，但它也匹配正则表达式左边的空格。它没有在左侧的文本中绑定匹配的字符串，但它使用\b绑定匹配字符串的右侧

正则表达式：

(price|rs)?\s*(\d+[\s\d.]*\s*?(pkg|k|m|(?:la(?:c|kh|k)|crore|cr)s?|l)\b\.?)

输入文本：

    This should matchprice  5.6 lacincluding price(i.e  price 5.6 lac) and rs 56 m. including rs (i.e rs 56 k  rs 56 m) .

It will match normally if there is no price or rs written for example or                   56 k or   8.8 crs.   are  correct matching but its should bound the matched string from left side as well just like its not matching sapce after end of the matched string.

It should not match the spaces left of 8.5 in this      8.5 lac ould not match eitherrs 6 lac asas there is no spaces before 5.6

How can I modify above regex to bound the matched word in the left side as well? 

Answer 1

您可以将\s*移动到可选的非捕获组：

(?:\b(price|rs)\s*)?(\d+[\s\d.]*\s*?(pkg|k|m|(?:la(?:c|kh|k)|crore|cr)s?|l)\b\.?)
^^^^^^^^^^^^^^^^^^^^

见regex demo

(?:\b(price|rs)\s*)?模式将匹配单词边界，接着是price或rs，后面跟着0+空白字符，整个模式将尝试一次，并且由于?修饰符，模式是可选的（整个模式序列可以匹配1或0次）