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std::basic_string<CharT,Traits,Allocator>::replace

(1) 
basic_string& replace( size_type pos, size_type count,
                       const basic_string& str );
 (until C++20) 
constexpr basic_string& replace( size_type pos, size_type count,
                                 const basic_string& str );
 (since C++20)
(1) 
basic_string& replace( const_iterator first, const_iterator last,
                       const basic_string& str );
 (until C++20) 
constexpr basic_string& replace( const_iterator first, const_iterator last,
                                 const basic_string& str );
 (since C++20)
(2) 
basic_string& replace( size_type pos, size_type count,
                       const basic_string& str,
                       size_type pos2, size_type count2 );
 (until C++14) 
basic_string& replace( size_type pos, size_type count,
                       const basic_string& str,
                       size_type pos2, size_type count2 = npos );
 (since C++14)
(until C++20) 
constexpr basic_string& replace( size_type pos, size_type count,
                                 const basic_string& str,
                                 size_type pos2, size_type count2 = npos );
 (since C++20)
(3) 
template< class InputIt >
basic_string& replace( const_iterator first, const_iterator last,
                       InputIt first2, InputIt last2 );
 (until C++20) 
template< class InputIt >
constexpr basic_string& replace( const_iterator first, const_iterator last,
                                 InputIt first2, InputIt last2 );
 (since C++20)
(4) 
basic_string& replace( size_type pos, size_type count,
                       const CharT* cstr, size_type count2 );
 (until C++20) 
constexpr basic_string& replace( size_type pos, size_type count,
                                 const CharT* cstr, size_type count2 );
 (since C++20)
(4) 
basic_string& replace( const_iterator first, const_iterator last,
                       const CharT* cstr, size_type count2 );
 (until C++20) 
constexpr basic_string& replace( const_iterator first, const_iterator last,
                                 const CharT* cstr, size_type count2 );
 (since C++20)
(5) 
basic_string& replace( size_type pos, size_type count,
                       const CharT* cstr );
 (until C++20) 
constexpr basic_string& replace( size_type pos, size_type count,
                                 const CharT* cstr );
 (since C++20)
(5) 
basic_string& replace( const_iterator first, const_iterator last,
                       const CharT* cstr );
 (until C++20) 
constexpr basic_string& replace( const_iterator first, const_iterator last,
                                 const CharT* cstr );
 (since C++20)
(6) 
basic_string& replace( size_type pos, size_type count,
                       size_type count2, CharT ch );
 (until C++20) 
constexpr basic_string& replace( size_type pos, size_type count,
                                 size_type count2, CharT ch );
 (since C++20)
(6) 
basic_string& replace( const_iterator first, const_iterator last,
                       size_type count2, CharT ch );
 (until C++20) 
constexpr basic_string& replace( const_iterator first, const_iterator last,
                                 size_type count2, CharT ch );
 (since C++20)
(7) 
basic_string& replace( const_iterator first, const_iterator last, 
                       std::initializer_list<CharT> ilist );
 (since C++11)
(until C++20) 
constexpr basic_string& replace( const_iterator first, const_iterator last, 
                                 std::initializer_list<CharT> ilist );
 (since C++20)
(8) 
template < class StringViewLike >
basic_string& replace( size_type pos, size_type count,
                       const StringViewLike& t );
 (since C++17)
(until C++20) 
template < class StringViewLike >
constexpr basic_string& replace( size_type pos, size_type count,
                                 const StringViewLike& t );
 (since C++20)
(8) 
template < class StringViewLike >
basic_string& replace( const_iterator first, const_iterator last,
                       const StringViewLike& t );
 (since C++17)
(until C++20) 
template < class StringViewLike >
constexpr basic_string& replace( const_iterator first, const_iterator last,
                                 const StringViewLike& t );
 (since C++20)
(9) 
template < class StringViewLike >
basic_string& replace( size_type pos, size_type count, const StringViewLike& t,
                       size_type pos2, size_type count2 = npos );
 (since C++17)
(until C++20) 
template < class StringViewLike >
constexpr basic_string& replace( size_type pos, size_type count, const StringViewLike& t,
                                 size_type pos2, size_type count2 = npos );
 (since C++20)

Replaces the part of the string indicated by either [pos, pos + count) or [first, last) with a new string.

The new string can be one of:

1) string str;
2) substring [pos2, pos2 + count2) of str, except if count2==npos or if would extend past str.size(), [pos2, str.size()) is used.
3) characters in the range [first2, last2).

This overload has the same effect as overload (6) if InputIt is an integral type.

 (until C++11)

This overload only participates in overload resolution if InputIt qualifies as an LegacyInputIterator.

 (since C++11)
4) characters in the range [cstr, cstr + count2);
5) characters in the range [cstr, cstr + Traits::length(cstr));
6) count2 copies of character ch;
7) characters in the initializer list ilist;
8) characters of a string view sv, converted from t as if by std::basic_string_view<CharT, Traits> sv = t;. These overloads participate in overload resolution only if std::is_convertible_v<const StringViewLike&, std::basic_string_view<CharT, Traits>> is true and std::is_convertible_v<const StringViewLike&, const CharT*> is false
9) subview [pos2, pos2 + count2) of a string view sv, converted from t as if by std::basic_string_view<CharT, Traits> sv = t;, except if count2==npos or if it would extend past sv.size(), [pos2, sv.size()) is used. This overload participates in overload resolution only if std::is_convertible_v<const StringViewLike&, std::basic_string_view<CharT, Traits>> is true and std::is_convertible_v<const StringViewLike&, const CharT*> is false.

Parameters

pos - start of the substring that is going to be replaced
count - length of the substring that is going to be replaced
first, last - range of characters that is going to be replaced
str - string to use for replacement
pos2 - start of the substring to replace with
count2 - number of characters to replace with
cstr - pointer to the character string to use for replacement
ch - character value to use for replacement
first2, last2 - range of characters to use for replacement
ilist - initializer list with the characters to use for replacement
t - object (convertible to std::basic_string_view) with the characters to use for replacement

Return value

*this.

Exceptions

In any case, if an exception is thrown for any reason, this function has no effect (strong exception guarantee). (since C++11).

Example

#include <cassert>
#include <cstddef>
#include <iostream>
#include <string>
#include <string_view>
 
std::size_t replace_all(std::string& inout, std::string_view what, std::string_view with);
std::size_t remove_all(std::string& inout, std::string_view what);
void test_replace_remove_all();
 
int main()
{
    std::string str{"The quick brown fox jumps over the lazy dog."};
 
    str.replace(10, 5, "red"); // (5)
 
    str.replace(str.begin(), str.begin() + 3, 1, 'A'); // (6)
 
    std::cout << str << "\n\n";
 
    test_replace_remove_all();
}
 
 
std::size_t replace_all(std::string& inout, std::string_view what, std::string_view with)
{
    std::size_t count{};
    for (std::string::size_type pos{};
         inout.npos != (pos = inout.find(what.data(), pos, what.length()));
         pos += with.length(), ++count) {
        inout.replace(pos, what.length(), with.data(), with.length());
    }
    return count;
}
 
std::size_t remove_all(std::string& inout, std::string_view what) {
    return replace_all(inout, what, "");
}
 
void test_replace_remove_all()
{
    std::string str2{"ftp: ftpftp: ftp:"};
    std::cout << "#1 " << str2 << '\n';
 
    auto count = replace_all(str2, "ftp", "http");
    assert(count == 4);
    std::cout << "#2 " << str2 << '\n';
 
    count = replace_all(str2, "ftp", "http");
    assert(count == 0);
    std::cout << "#3 " << str2 << '\n';
 
    count = remove_all(str2, "http");
    assert(count == 4);
    std::cout << "#4 " << str2 << '\n';
}

Output:

A quick red fox jumps over the lazy dog.
 
#1 ftp: ftpftp: ftp:
#2 http: httphttp: http:
#3 http: httphttp: http:
#4 : : :

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 1323 C++98 several overloads of replace use iterator and not const_iterator use const_iterator
LWG 2946 C++17 string_view overload causes ambiguity in some cases avoided by making it a template

See also

(C++11)
replaces occurrences of a regular expression with formatted replacement text
(function template)
replaces all values satisfying specific criteria with another value
(function template)

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Last Updated 2022-06-02T22:02:33Z