std::basic_string::replace(3)

NAME
std::basic_string::replace - std::basic_string::replace

Synopsis
basic_string& replace( size_type pos, size_type (until count, C++20) const basic_string& str ); constexpr basic_string& replace( size_type pos, (since size_type count, C++20) const basic_string& str ); basic_string& replace( const_iterator first, (until const_iterator last, C++20) const basic_string& str ); constexpr basic_string& replace( const_iterator (since first, const_iterator last, C++20) const basic_string& str ); basic_string& replace( size_type pos, size_type count,
                        (until const basic_string& str, C++14) size_type pos2, size_type count2 ); basic_string& replace( size_type pos, size_type count, (since
                        C++14) const basic_string& str, (until
                        C++20) size_type pos2, size_type count2 = npos ); constexpr basic_string& replace( size_type pos, size_type count,
                        (since const basic_string& str, C++20) size_type pos2, size_type count2 = npos ); template< class InputIt > basic_string& replace( const_iterator first, (until const_iterator last, C++20) InputIt first2, InputIt last2 ); template< class InputIt > constexpr basic_string& replace( const_iterator (since first, const_iterator last, C++20) InputIt first2, InputIt last2 ); basic_string& replace( size_type pos, size_type (until count, C++20) const CharT* cstr, size_type count2 ); constexpr basic_string& replace( size_type pos, (since size_type count, C++20) const CharT* cstr, size_type count2 ); basic_string& replace( const_iterator first, (until const_iterator last, C++20) const CharT* cstr, size_type count2 ); constexpr basic_string& replace( const_iterator (since first, const_iterator last, C++20) const CharT* cstr, size_type count2 ); basic_string& replace( size_type pos, size_type (until count, C++20) const CharT* cstr ); constexpr basic_string& replace( size_type pos, (since size_type count, C++20) const CharT* cstr ); basic_string& replace( const_iterator first, (until const_iterator last, (1) C++20) const CharT* cstr ); constexpr basic_string& replace( const_iterator (since first, const_iterator last, (1) C++20) const CharT* cstr ); basic_string& replace( size_type pos, size_type (until count, (2) C++20) size_type count2, CharT ch ); constexpr basic_string& replace( size_type pos, (since size_type count, C++20) size_type count2, CharT ch ); basic_string& replace( const_iterator first, (until const_iterator last, C++20) size_type count2, CharT ch ); (3) constexpr basic_string& replace( const_iterator (since first, const_iterator last, C++20) size_type count2, CharT ch ); basic_string& replace( (since const_iterator first, C++11) const_iterator last, (4) (until std::initializer_list<CharT> C++20) ilist ); constexpr basic_string& replace( const_iterator (since first, const_iterator last, (4) C++20) std::initializer_list<CharT> ilist ); template < class StringViewLike >
                        (5) (since basic_string& replace( C++17) size_type pos, size_type (until count, C++20)
                        (5) const StringViewLike& t ); template < class StringViewLike >
                        (6) constexpr basic_string& (since replace( size_type pos, C++20) size_type count, const StringViewLike& t ); (6) template < class StringViewLike >
                        (since basic_string& replace( C++17) const_iterator first, (7) (until const_iterator last, C++20) const StringViewLike& t ); template < class StringViewLike > (8) constexpr basic_string& (since replace( const_iterator C++20) first, const_iterator last, const StringViewLike& t ); template < class StringViewLike > (8) basic_string& replace( (since size_type pos, size_type C++17) count, const StringViewLike& (until t, C++20) size_type pos2, size_type count2 = npos ); (9) template < class StringViewLike > constexpr basic_string& replace( size_type pos, (since size_type count, const C++20) StringViewLike& t, size_type pos2, size_type count2 = npos );
   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 (until C++11)
   integral type.
   This overload only participates in overload resolution if InputIt (since C++11)
   qualifies as an LegacyInputIterator.
   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
     * std::out_of_range if pos > length() or pos2 > str.length()
     * std::length_error if the resulting string will exceed maximum possible string
       length (max_size())
   In any case, if an exception is thrown for any reason, this function has no effect
   (strong exception guarantee).
   (since C++11)

Example
// Run this code
 #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 use const_iterator
                       and not const_iterator
   LWG 2946 C++17 string_view overload causes ambiguity in avoided by making it a
                       some cases template

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