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std::basic_string::replace

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

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.
4) first count2 characters of the character string pointed to by cstr;
5) null-terminated character string pointed to by 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 only participate in overload resolution if std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>> is true and std::is_convertible_v<const T&, 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 only participates in overload resolution if std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>> is true and std::is_convertible_v<const T&, 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

std::out_of_range if pos > length() or pos2 > str.length().

std::length_error if the resulting string will exceed maximum possible string length (std::string::npos - 1).

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

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 2946 C++17 string_view overload causes ambiguity in some cases avoided by making it a template

Example

#include <iostream>
#include <string>
 
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';
}

Output:

A quick red fox jumps over the lazy dog.

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