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Difference between revisions of "cpp/string/basic string/insert"

From cppreference.com
< cpp‎ | string‎ | basic string
(+type reqs)
m (→‎Synopsis: +constexpr since...)
 
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−
{{cpp/string/basic_string/title | insert}}
+
{{cpp/string/basic_string/title|insert}}
 
{{cpp/string/basic_string/navbar}}
 
{{cpp/string/basic_string/navbar}}
−
{{ddcl list begin}}
+
{{dcl begin}}
−
{{ddcl list item | num=1 | notes={{mark until c++11}} <br> {{mark since c++11}} |
+
{{dcl|num=1|notes={{mark constexpr since c++20}}|
−
iterator insert( iterator pos, CharT ch );
+
−
iterator insert( const_iterator pos, CharT ch );
+
−
}}
+
−
{{ddcl list item | num=2 |
+
−
void insert( iterator pos, size_type count, CharT ch );
+
−
}}
+
−
{{ddcl list item | num=3 |
+
 
basic_string& insert( size_type index, size_type count, CharT ch );
 
basic_string& insert( size_type index, size_type count, CharT ch );
 
}}
 
}}
−
{{ddcl list item | num=4 |
+
{{dcl|num=2|notes={{mark constexpr since c++20}}|
 
basic_string& insert( size_type index, const CharT* s );
 
basic_string& insert( size_type index, const CharT* s );
 
}}
 
}}
−
{{ddcl list item | num=5 |
+
{{dcl|num=3|notes={{mark constexpr since c++20}}|
 
basic_string& insert( size_type index, const CharT* s, size_type count );
 
basic_string& insert( size_type index, const CharT* s, size_type count );
 
}}
 
}}
−
{{ddcl list item | num=6 |
+
{{dcl|num=4|notes={{mark constexpr since c++20}}|
 
basic_string& insert( size_type index, const basic_string& str );
 
basic_string& insert( size_type index, const basic_string& str );
 
}}
 
}}
−
{{ddcl list item | num=7 |
+
{{dcl rev multi|num=5
 +
|dcl1=
 
basic_string& insert( size_type index, const basic_string& str,
 
basic_string& insert( size_type index, const basic_string& str,
−
                       size_type index_str, size_type count );
+
                       size_type s_index, size_type count );
 +
|since2=c++14|notes2={{mark constexpr since c++20}}|dcl2=
 +
basic_string& insert( size_type index, const basic_string& str,
 +
                      size_type s_index, size_type count = npos );
 +
}}
 +
{{dcl rev multi|num=6
 +
|dcl1=
 +
iterator insert( iterator pos, CharT ch );
 +
|since2=c++11|notes2={{mark constexpr since c++20}}|dcl2=
 +
iterator insert( const_iterator pos, CharT ch );
 +
}}
 +
{{dcl rev multi|num=7
 +
|dcl1=
 +
void insert( iterator pos, size_type count, CharT ch );
 +
|since2=c++11|notes2={{mark constexpr since c++20}}|dcl2=
 +
iterator insert( const_iterator pos, size_type count, CharT ch );
 
}}
 
}}
−
{{ddcl list item | num=8 | notes={{mark until c++11}} <br><br> {{mark since c++11}} |
+
{{dcl rev multi|num=8
 +
|dcl1=
 
template< class InputIt >
 
template< class InputIt >
−
void insert( iterator i, InputIt first, InputIt last );
+
void insert( iterator pos, InputIt first, InputIt last );
 +
|since2=c++11|notes2={{mark constexpr since c++20}}|dcl2=
 
template< class InputIt >
 
template< class InputIt >
−
iterator insert( const_iterator i, InputIt first, InputIt last );
+
iterator insert( const_iterator pos, InputIt first, InputIt last );
 
}}
 
}}
−
{{ddcl list item | num=9 | notes={{mark since c++11}} |
+
{{dcl|num=9|since=c++11|notes={{mark constexpr since c++20}}|
 
iterator insert( const_iterator pos, std::initializer_list<CharT> ilist );
 
iterator insert( const_iterator pos, std::initializer_list<CharT> ilist );
 
}}
 
}}
−
{{ddcl list end}}
+
{{dcl|num=10|since=c++17|notes={{mark constexpr since c++20}}|
 +
template< class StringViewLike >
 +
basic_string& insert( size_type index, const StringViewLike& t );
 +
}}
 +
{{dcl|num=11|since=c++17|notes={{mark constexpr since c++20}}|1=
 +
template< class StringViewLike >
 +
basic_string& insert( size_type index, const StringViewLike& t,
 +
                      size_type t_index, size_type count = npos );
 +
}}
 +
{{dcl end}}
  
−
Inserts characters into the string:
+
Inserts characters into the string.
  
−
1) inserts character {{tt|ch}} before the character pointed by {{tt|pos}}
+
@1@ Inserts {{c|count}} copies of character {{c|ch}} at the position {{c|index}}.
  
−
2) inserts {{tt|count}} copies of character {{tt|ch}} before the element pointed to by {{tt|pos}}
+
@2@ Inserts null-terminated character string pointed to by {{c|s}} at the position {{c|index}}. The length of the string is determined by the first null character using {{c|Traits::length(s)}}.
  
−
3) inserts {{tt|count}} copies of character {{tt|ch}} at the position {{tt|index}}
+
@3@ Inserts the characters in the range {{range|s|s + count}} at the position {{c|index}}. The range can contain null characters.
  
−
4) inserts null-terminated character string pointed to by {{tt|s}} at the position {{tt|index}}. The length of the string is determined by the first null character.  
+
@4@ Inserts string {{c|str}} at the position {{c|index}}.
  
−
5) inserts the first {{tt|count}} characters from the character string pointed to by {{tt|s}} at the position {{tt|index}}. {{tt|s}} can contain null characters.
+
@5@ Inserts a string, obtained by {{c|str.substr(s_index, count)}} at the position {{c|index}}.
  
−
6) inserts string {{tt|str}} at the position {{tt|index}}
+
@6@ Inserts character {{c|ch}} before the character pointed by {{c|pos}}.
  
−
7) inserts a string, obtained by {{c|str.substr(index_str, count)}} at the position {{tt|index}}
+
@7@ Inserts {{c|count}} copies of character {{c|ch}} before the element (if any) pointed by {{c|pos}}.
  
−
8) inserts characters from the range {{tt|[first, last)}}  
+
@8@ Inserts characters from the range {{range|first|last}} before the element (if any) pointed by {{c|pos}}, as if by {{c|insert(pos - begin(), basic_string(first, last, get_allocator()))}}.
 +
{{rrev|since=c++11|
 +
This overload does not participate in overload resolution if {{tt|InputIt}} does not satisfy {{named req|InputIterator}}.
 +
}}
 +
 
 +
@9@ Inserts elements from initializer list {{c|ilist}} before the element (if any) pointed by {{c|pos}}.
 +
 
 +
@10@ {{cpp/string/sv hack|inserts the elements from {{c|sv}} before the element (if any) pointed by {{c|index}}, as if by {{c|insert(index, sv.data(), sv.size())}}}}
 +
 
 +
@11@ {{cpp/string/sv hack|inserts, before the element (if any) pointed by {{c|index}}, the characters from the subview {{range|t_index|t_index + count}} of {{c|sv}}.
 +
* If the requested subview lasts past the end of {{c|sv}}, or if {{c|1=count == npos}}, the resulting subview is {{range|t_index|sv.size()}}.
 +
* If {{c|t_index > sv.size()}}, or if {{c|index > size()}}, {{lc|std::out_of_range}} is thrown}}
  
−
9) inserts elements from initializer list {{tt|ilist}}.  
+
If {{c|pos}} is not a valid iterator on {{c|*this}}, the behavior is undefined.  
  
 
===Parameters===
 
===Parameters===
−
{{param list begin}}
+
{{par begin}}
−
{{param list item | pos | iterator before which the characters will be inserted}}
+
{{par|index|position at which the content will be inserted}}
−
{{param list item | index | position at which the content will be inserted}}
+
{{par|pos|iterator before which the characters will be inserted}}
−
{{param list item | ch | character to insert}}
+
{{par|ch|character to insert}}
−
{{param list item | s | pointer to the character string to insert}}
+
{{par|count|number of characters to insert}}
−
{{param list item | str | string to insert}}
+
{{par|s|pointer to the character string to insert}}
−
{{param list item | first, last | range defining characters to be insert}}
+
{{par|str|string to insert}}
−
{{param list item | count | number of characters to insert}}
+
{{par|first, last|range defining characters to insert}}
−
{{param list item | index_str | position of the first character in the string {{tt|str}} to insert.}}
+
{{par|s_index|position of the first character in {{c|str}} to insert}}
−
{{param list item | ilist | initializer list to insert the characters from}}
+
{{par|ilist|{{lc|std::initializer_list}} to insert the characters from}}
−
{{param list hreq}}
+
{{par|t|object (convertible to {{lc|std::basic_string_view}}) to insert the characters from}}
−
{{param list req concept | InputIt | InputIterator}}
+
{{par|t_index|position of the first character in {{c|t}} to insert}}
−
{{param list end}}  
+
{{par hreq}}
 +
{{par req named|InputIt|InputIterator}}
 +
{{par end}}
  
 
===Return value===
 
===Return value===
 +
@1-5@ {{c|*this}}
  
−
1) iterator following the last inserted character.
+
@6-9@ An iterator which refers to the copy of the first inserted character or {{c|pos}} if no characters were inserted ({{c|1=count == 0}} or {{c|1=first == last}} or {{c|1=ilist.size() == 0}})
  
−
2-7) {{c|*this}}
+
@10,11@ {{c|*this}}
  
−
8-9) iterator following the last inserted character.
+
===Exceptions===
 +
@1-4,10@ Throws {{lc|std::out_of_range}} if {{c|index > size()}}.
 +
@5@ Throws {{lc|std::out_of_range}} if {{c|index > size()}} or if {{c|s_index > str.size()}}.
 +
@11@ Throws {{lc|std::out_of_range}} if {{c|index > size()}} or if {{c|t_index > sv.size()}}.
  
−
===Complexity===
+
In all cases, throws {{lc|std::length_error}} if {{c|size() + ins_count > max_size()}} where {{c|ins_count}} is the number of characters that will be inserted.
  
−
{{todo}}
+
{{rrev|since=c++20|
 +
In all cases, if {{c/core|std::allocator_traits<Allocator>::allocate}} throws an exception, it is rethrown.
 +
}}
  
−
===See also===
+
{{cpp/strong exception safety guarantee}}
  
−
{{dcl list begin}}
+
===Example===
−
{{dcl list template | cpp/string/basic_string/dcl list append}}
+
{{example
−
{{dcl list template | cpp/string/basic_string/dcl list push_back}}
+
|code=
−
{{dcl list end}}
+
#include <cassert>
 +
#include <iterator>
 +
#include <string>
 +
 
 +
using namespace std::string_literals;
 +
 
 +
int main()
 +
{
 +
    std::string s = "xmplr";
 +
   
 +
    // insert(size_type index, size_type count, char ch)
 +
    s.insert(0, 1, 'E');
 +
    assert("Exmplr" == s);
 +
   
 +
    // insert(size_type index, const char* s)
 +
    s.insert(2, "e");
 +
    assert("Exemplr" == s);
 +
   
 +
    // insert(size_type index, string const& str)
 +
    s.insert(6, "a"s);
 +
    assert("Exemplar" == s);
 +
   
 +
    // insert(size_type index, string const& str,
 +
    //        size_type s_index, size_type count)
 +
    s.insert(8, " is an example string."s, 0, 14);
 +
    assert("Exemplar is an example" == s);
 +
   
 +
    // insert(const_iterator pos, char ch)
 +
    s.insert(s.cbegin() + s.find_first_of('n') + 1, ':');
 +
    assert("Exemplar is an: example" == s);
 +
   
 +
    // insert(const_iterator pos, size_type count, char ch)
 +
    s.insert(s.cbegin() + s.find_first_of(':') + 1, 2, '=');
 +
    assert("Exemplar is an:== example" == s);
 +
   
 +
    // insert(const_iterator pos, InputIt first, InputIt last)
 +
    {
 +
        std::string seq = " string";
 +
        s.insert(s.begin() + s.find_last_of('e') + 1,
 +
            std::begin(seq), std::end(seq));
 +
        assert("Exemplar is an:== example string" == s);
 +
    }
 +
   
 +
    // insert(const_iterator pos, std::initializer_list<char>)
 +
    s.insert(s.cbegin() + s.find_first_of('g') + 1, {'.'});
 +
    assert("Exemplar is an:== example string." == s);
 +
}
 +
|output=
 +
}}
 +
 
 +
===Defect reports===
 +
{{dr list begin}}
 +
{{dr list item|wg=lwg|dr=7|std=C++98|before=overload {{v|8}} referred to a non-existing overload|after=refers to overload {{v|4}} correctly}}
 +
{{dr list item|wg=lwg|dr=847|std=C++98|before=there was no exception safety guarantee|after=added strong exception safety guarantee}}
 +
{{dr list item|wg=lwg|dr=2946|std=C++17|before=overload {{v|10}} caused ambiguity in some cases|after=avoided by making it a template}}
 +
{{dr list end}}
 +
 
 +
===See also===
 +
{{dsc begin}}
 +
{{dsc inc|cpp/string/basic_string/dsc insert_range}}
 +
{{dsc inc|cpp/string/basic_string/dsc append}}
 +
{{dsc inc|cpp/string/basic_string/dsc push_back}}
 +
{{dsc end}}
  
−
[[de:cpp/string/basic string/insert]]
+
{{langlinks|de|es|fr|it|ja|pt|ru|zh}}
−
[[ja:cpp/string/basic string/insert]]
+
−
[[pt:cpp/string/basic string/insert]]
+
−
[[ru:cpp/string/basic string/insert]]
+

Latest revision as of 06:23, 22 April 2024

 
C++
 
Strings library
 
std::basic_string
Member functions
(C++23)
Element access
(DR*)
(DR*)
(C++17)
Iterators
(C++11)
(C++11)
(C++11)
(C++11)
Capacity
(DR*)
Modifiers
basic_string::insert
(C++23)
(DR*)
(C++23)
(C++23)
(C++23)  
Search
Operations
(C++20)
(C++20)
(C++23)
Constants
Non-member functions
(C++20)(C++20)
I/O
Comparison
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Numeric conversions
(C++11)(C++11)(C++11)
(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)
(C++11)
Literals
(C++14)
Helper classes
(C++11)
Deduction guides (C++17)

 
basic_string& insert( size_type index, size_type count, CharT ch );
 (1) (constexpr since C++20)
basic_string& insert( size_type index, const CharT* s );
 (2) (constexpr since C++20)
basic_string& insert( size_type index, const CharT* s, size_type count );
 (3) (constexpr since C++20)
basic_string& insert( size_type index, const basic_string& str );
 (4) (constexpr since C++20)
(5)
basic_string& insert( size_type index, const basic_string& str,
                      size_type s_index, size_type count );
 (until C++14)
basic_string& insert( size_type index, const basic_string& str,
                      size_type s_index, size_type count = npos );
 (since C++14)
(constexpr since C++20)
(6)
iterator insert( iterator pos, CharT ch );
 (until C++11)
iterator insert( const_iterator pos, CharT ch );
 (since C++11)
(constexpr since C++20)
(7)
void insert( iterator pos, size_type count, CharT ch );
 (until C++11)
iterator insert( const_iterator pos, size_type count, CharT ch );
 (since C++11)
(constexpr since C++20)
(8)
template< class InputIt >
void insert( iterator pos, InputIt first, InputIt last );
 (until C++11)
template< class InputIt >
iterator insert( const_iterator pos, InputIt first, InputIt last );
 (since C++11)
(constexpr since C++20)
iterator insert( const_iterator pos, std::initializer_list<CharT> ilist );
 (9) (since C++11)
(constexpr since C++20)
template< class StringViewLike >
basic_string& insert( size_type index, const StringViewLike& t );
 (10) (since C++17)
(constexpr since C++20)
template< class StringViewLike >

basic_string& insert( size_type index, const StringViewLike& t,

                      size_type t_index, size_type count = npos );
 (11) (since C++17)
(constexpr since C++20)

Inserts characters into the string.

1) Inserts count copies of character ch at the position index.
2) Inserts null-terminated character string pointed to by s at the position index. The length of the string is determined by the first null character using Traits::length(s).
3) Inserts the characters in the range [s, s + count) at the position index. The range can contain null characters.
4) Inserts string str at the position index.
5) Inserts a string, obtained by str.substr(s_index, count) at the position index.
6) Inserts character ch before the character pointed by pos.
7) Inserts count copies of character ch before the element (if any) pointed by pos.
8) Inserts characters from the range [first, last) before the element (if any) pointed by pos, as if by insert(pos - begin(), basic_string(first, last, get_allocator())).

This overload does not participate in overload resolution if InputIt does not satisfy LegacyInputIterator.

(since C++11)
9) Inserts elements from initializer list ilist before the element (if any) pointed by pos.
10) Implicitly converts t to a string view sv as if by std::basic_string_view<CharT, Traits> sv = t;, then inserts the elements from sv before the element (if any) pointed by index, as if by insert(index, sv.data(), sv.size()).
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.
11) Implicitly converts t to a string view sv as if by std::basic_string_view<CharT, Traits> sv = t;, then inserts, before the element (if any) pointed by index, the characters from the subview [t_index, t_index + count) of sv.
  • If the requested subview lasts past the end of sv, or if count == npos, the resulting subview is [t_index, sv.size()).
  • If t_index > sv.size(), or if index > size(), std::out_of_range is thrown.
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.

If pos is not a valid iterator on *this, the behavior is undefined.

Contents

[edit] Parameters

index - position at which the content will be inserted
pos - iterator before which the characters will be inserted
ch - character to insert
count - number of characters to insert
s - pointer to the character string to insert
str - string to insert
first, last - range defining characters to insert
s_index - position of the first character in str to insert
ilist - std::initializer_list to insert the characters from
t - object (convertible to std::basic_string_view) to insert the characters from
t_index - position of the first character in t to insert
Type requirements
-
InputIt must meet the requirements of LegacyInputIterator.

[edit] Return value

1-5) *this
6-9) An iterator which refers to the copy of the first inserted character or pos if no characters were inserted (count == 0 or first == last or ilist.size() == 0)
10,11) *this

[edit] Exceptions

1-4,10) Throws std::out_of_range if index > size().
5) Throws std::out_of_range if index > size() or if s_index > str.size().
11) Throws std::out_of_range if index > size() or if t_index > sv.size().

In all cases, throws std::length_error if size() + ins_count > max_size() where ins_count is the number of characters that will be inserted.

In all cases, if std::allocator_traits<Allocator>::allocate throws an exception, it is rethrown.

(since C++20)

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

[edit] Example

Run this code
#include <cassert>
#include <iterator>
#include <string>
 
using namespace std::string_literals;
 
int main()
{
    std::string s = "xmplr";
 
    // insert(size_type index, size_type count, char ch)
    s.insert(0, 1, 'E');
    assert("Exmplr" == s);
 
    // insert(size_type index, const char* s)
    s.insert(2, "e");
    assert("Exemplr" == s);
 
    // insert(size_type index, string const& str)
    s.insert(6, "a"s);
    assert("Exemplar" == s);
 
    // insert(size_type index, string const& str,
    //        size_type s_index, size_type count)
    s.insert(8, " is an example string."s, 0, 14);
    assert("Exemplar is an example" == s);
 
    // insert(const_iterator pos, char ch)
    s.insert(s.cbegin() + s.find_first_of('n') + 1, ':');
    assert("Exemplar is an: example" == s);
 
    // insert(const_iterator pos, size_type count, char ch)
    s.insert(s.cbegin() + s.find_first_of(':') + 1, 2, '=');
    assert("Exemplar is an:== example" == s);
 
    // insert(const_iterator pos, InputIt first, InputIt last)
    {
        std::string seq = " string";
        s.insert(s.begin() + s.find_last_of('e') + 1,
            std::begin(seq), std::end(seq));
        assert("Exemplar is an:== example string" == s);
    }
 
    // insert(const_iterator pos, std::initializer_list<char>)
    s.insert(s.cbegin() + s.find_first_of('g') + 1, {'.'});
    assert("Exemplar is an:== example string." == s);
}

[edit] 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 7 C++98 overload (8) referred to a non-existing overload refers to overload (4) correctly
LWG 847 C++98 there was no exception safety guarantee added strong exception safety guarantee
LWG 2946 C++17 overload (10) caused ambiguity in some cases avoided by making it a template

[edit] See also

(C++23)
 inserts a range of characters
(public member function) [edit]
appends characters to the end
(public member function) [edit]
appends a character to the end
(public member function) [edit]
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