# std::sub_match<BidirIt>::length

From cppreference.com
< cpp‎ | regex‎ | sub match

difference_type length() const; |  |

### Parameters

(none)

### Return value

Returns the number of characters in the match, i.e. std::distance(first, second) if the match is valid, 0 otherwise.

### Complexity

Constant.

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