Replace a specific character with another from regex match?

Question

I am trying to replace * with whenever \w*\w pattern is found. Here is what I have

#include <string>
#include <iostream>
#include <regex>

using namespace std;

int main() {
    string text = "Dear Customer, You have made a Debit Card purchase of INR962.00 on 26 Oct. Info.VPS*Brown House. Your Net Available Balance is INR 5,584.58.";

    regex reg("[\w*\w]");
    text = regex_replace(text, reg, " ");
    cout << text << "\n";
}

But it replace the * with and w with also.

Output of the above program is

Dear Customer, You have made a Debit Card purchase of INR962.00 on 26 Oct. Info.VPS Bro n House. Your Net Available Balance is INR 5,584.58.

regex reg(R"((\w)\*(?=\w))"); and replace with "$1 "

Wiktor Stribiżew
– Wiktor Stribiżew

2017-03-15 17:55:36 +00:00
Commented Mar 15, 2017 at 17:55 — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Mar 15, 2017 at 17:55
regex [ ] does not mean what you think it means,

Ahmed Masud
– Ahmed Masud

2017-03-15 17:59:10 +00:00
Commented Mar 15, 2017 at 17:59 — Ahmed Masud
– Ahmed Masud, Commented Mar 15, 2017 at 17:59
[\w*\w] means replace any of the characters w or *.

stark
– stark

2017-03-15 18:01:25 +00:00
Commented Mar 15, 2017 at 18:01 — stark
– stark, Commented Mar 15, 2017 at 18:01

Wiktor Stribiżew · Accepted Answer · 2017-03-15 18:34:28Z

2

Use

regex reg(R"(([a-zA-Z])\*(?=[a-zA-Z]))");
text = regex_replace(text, reg, "$1 ");
// => Dear Customer, You have made a Debit Card purchase of INR962.00 on 26 Oct. Info.VPS Brown House. Your Net Available Balance is INR 5,584.58.

See C++ online demo

The R"(([a-zA-Z])\*(?=[a-zA-Z]))" is a raw string literal where \ is treated as a literal \ symbol, not an escaping symbol for entities like \n or \r.

The pattern ([a-zA-Z])\*(?=[a-zA-Z]) matches and captures an ASCII letter char (with ([a-zA-Z])), then matches a * (with \*) and then requires (does not consume) an ASCII letter char (with (?=[a-zA-Z])).

The $1 is the backreference to the value captured with the ([a-zA-Z]) group.

edited Mar 15, 2017 at 18:34

answered Mar 15, 2017 at 17:57

Wiktor Stribiżew

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2 Comments

Shravan40 Over a year ago

Great answer. It also replaces the * with ` ` from pattern like 32423*random, random*34234 and 323423*43421 which I don't want.

Wiktor Stribiżew Over a year ago

But you used \w yourself. If you need to only match * in between ASCII letters, use [a-zA-Z] instead.

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