boost::regex_replace

Question

Currently I have a problem with boost :: regex, I need to find the appropriate word և replace. with the corresponding word. My code now looks like this.

std::string name = ptap;
std::string name_regex = "\\b" + name + "\\b"; 
boost::regex reg(name_regex);
checks_str = boost::regex_replace( checks_str, reg, alias_name );

There are words in the file that look like "ptap.power" because regex reads the dot as any character. The initial part of this word (ptap) changes, which I do not need. How to fix this?

Could you please clarify the problem? What are ptap, name and alias_name here? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jun 20, 2022 at 14:11
"ptap" is a string it should be in quotes, like this: std::string name = "ptap"; — Azat Zaroyan
– Azat Zaroyan, Commented Jun 20, 2022 at 15:56
These are the names of the layers that make up a small part of a large project. If you find "ptap" in the text, you should replace it with the words alias_name. If you come across the word "ptap.power" or another "." containing, that word remains the same. Thanks for the feedback) — Azat Zaroyan
– Azat Zaroyan, Commented Jun 20, 2022 at 16:05
Please provide a valid test case to see what problem you have got. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jun 20, 2022 at 17:56
sorry i could not use boost with online compiler but my main code will be written in boost — Azat Zaroyan
– Azat Zaroyan, Commented Jun 20, 2022 at 19:08

Wiktor Stribiżew · Accepted Answer · 2022-06-20 21:43:15Z

1

You can prevent a match if there is a dot after a word:

#include <boost/regex.hpp>
#include <string>
#include <iostream>

int main()
{
    std::string str = "ptap ptap.power";
    std::string name = "ptap";
    std::string rep = "pplug";
    std::string regex_name = "\\b" + name + "\\b(?!\\.)";
    boost::regex reg(regex_name);
    str = boost::regex_replace(str, reg, rep);
    std::cout << str << std::endl;
    return 0; 
}

See the C++ demo.

The (?!\.) is a negative lookahead that fails the match if there is a . char immediately to the right of the current location.

To avoid matching the keyword if there is a dot before, add a negative lookbehind:

std::string regex_name = "\\b(?<!\\.)" + name + "\\b(?!\\.)";

edited Jun 20, 2022 at 21:43

answered Jun 20, 2022 at 21:20

Wiktor Stribiżew

631k41 gold badges502 silver badges632 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Azat Zaroyan Over a year ago

Well, thank you very much for the previous answers. They worked very well in the previous cases but I have another problem.

Wiktor Stribiżew Over a year ago

@AzatZaroyan What is the problem?

Azat Zaroyan Over a year ago

What to do if in the previous case there is another character instead of a period, for example ptap:power, I need to replace it if it is ptap (it is not necessary at the beginning of the line, at the end or in the middle position), and in other cases if ptap: power, power:ptap, ptap-power will not be replaced

Wiktor Stribiżew Over a year ago

@AzatZaroyan You are not providing exact pattern requirements. If you just provide examples, I can provide a pattern - e.g. \b(?<![.:])ptap\b(?![.-]|:\s) (see demo) - but it won't work once you come back and say "oh, I have more examples...). Please formulate the rules for matching, update the question and let me know,

Azat Zaroyan Over a year ago

I just brought the examples to make my question clearer, I need it not to be distorted after the name in case of any character if such a case is possible or replace only if there are no extra characters after the name.)

Collectives™ on Stack Overflow

boost::regex_replace

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related