Can I replace a single character in a string with 2 characters?

Question

#include <algorithm>
#include <string>

void foo(std::string &s) {
    replace(s.begin(), s.end(), 'S', 'TH');
}

I want foo(s) to replace each S in s with the two characters TH. For example

std::string s = "SAT";
foo(s);
std::cout << s << "\n" // THAT

However, the definition of foo gives me an error.

Error (active) E0304 no instance of function template "std::replace" matches the argument list

Why does this not work?

Have you used std namespace? Try std::replace(s.begin(), s.end(), 'S', 'TH) — r_batra, Jul 30 '21 at 17:43
'TH' is not valid syntax >for character literals<. Only single characters are enclosed in single quotes. — gerum, Jul 30 '21 at 17:45
@gerum it is valid, mutlicharacter literals are conditionally supported, they are of type `int`: https://stackoverflow.com/a/34571914/4117728 — 463035818_is_not_an_ai, Jul 30 '21 at 17:47

score 2 · Accepted Answer · edited Jul 30 '21 at 18:04

2

std::replace cannot do it, but you can use std::regex_replace instead.

#include <regex>

std::string s = "SAT";
s = regex_replace(s, std::regex("S"), "TH");
std::cout << s << "\n"; // output: THAT

edited Jul 30 '21 at 18:04

HTNW

answered Jul 30 '21 at 17:51

aetrnm

1

you don't need a regex, `std::string::replace` can do it – 463035818_is_not_an_ai Jul 30 '21 at 18:07
1

@463035818_is_not_a_number, tbh, I tried to find a solution with string::replace, but didn't manage. It's never late to post your answer in a comment, I am learning from mistakes too! – aetrnm Jul 30 '21 at 18:34
1

https://godbolt.org/z/1434nfTT5, though return value of `find` should be checked. I find strings memebr functions confusing too, because they have similar names as algorithms but work with indices rather than iterators, can be rather confusing – 463035818_is_not_an_ai Jul 30 '21 at 18:37

1 Answers1