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

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< cpp‎ | string‎ | basic string
(Undo revision 91205 by Ssarpal (talk))
(2946)
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{{dcl rev end}}
 
{{dcl rev end}}
 
{{dcl | num=10 | since=c++17 |
 
{{dcl | num=10 | since=c++17 |
−
basic_string& insert( size_type pos, basic_string_view<CharT, Traits> sv );
+
template < class T >
 +
basic_string& insert( size_type pos, const T& t );
 
}}
 
}}
 
{{dcl | num=11 | since=c++17 |1=
 
{{dcl | num=11 | since=c++17 |1=
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@9@ Inserts elements from initializer list {{tt|ilist}} before the element pointed by {{tt|pos}}
 
@9@ Inserts elements from initializer list {{tt|ilist}} before the element pointed by {{tt|pos}}
  
−
@10@ Inserts the elements from the string view {{tt|sv}} before the element pointed by {{tt|pos}}, as if by {{c|insert(pos, sv.data(), sv.size())}}
+
@10@ {{cpp/string/sv hack|inserts the elements from {{tt|sv}} before the element pointed by {{tt|pos}}, as if by {{c|insert(pos, sv.data(), sv.size())}}}}
  
−
@11@ Converts {{tt|t}} to a string view {{tt|sv}} as if by {{c|1=std::basic_string_view<CharT, Traits> sv = t;}}, then inserts, before the element pointed by {{tt|pos}}, the characters from the subview {{tt|[index_str, index_str+count)}} of {{tt|sv}}. If the requested subview lasts past the end of {{tt|sv}}, or if {{c|1=count == npos}}, the resulting subview is {{tt|[index_str, sv.size())}}. If {{c|1=index_str > sv.size()}}, or if {{c|index > size()}}, {{lc|std::out_of_range}} is thrown. {{cpp/enable_if|{{c|std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>>}} is {{c|true}} and {{c|std::is_convertible_v<const T&, const CharT*>}} is {{c|false}}}}.
+
@11@ {{cpp/string/sv hack|inserts, before the element pointed by {{tt|pos}}, the characters from the subview {{tt|[index_str, index_str+count)}} of {{tt|sv}}. If the requested subview lasts past the end of {{tt|sv}}, or if {{c|1=count == npos}}, the resulting subview is {{tt|[index_str, sv.size())}}. If {{c|1=index_str > sv.size()}}, or if {{c|index > size()}}, {{lc|std::out_of_range}} is thrown}}
  
 
===Parameters===
 
===Parameters===
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{{par | index_str | position of the first character in the string {{tt|str}} to insert}}
 
{{par | index_str | position of the first character in the string {{tt|str}} to insert}}
 
{{par | ilist | {{lc|std::initializer_list}} to insert the characters from}}
 
{{par | ilist | {{lc|std::initializer_list}} to insert the characters from}}
−
{{par | sv | {{lc|std::basic_string_view}} to insert the characters from}}
 
 
{{par | t | object (convertible to {{lc|std::basic_string_view}}) to insert the characters from}}
 
{{par | t | object (convertible to {{lc|std::basic_string_view}}) to insert the characters from}}
 
{{par hreq}}
 
{{par hreq}}
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In any case, if an exception is thrown for any reason, this function has no effect (strong exception guarantee).}}
 
In any case, if an exception is thrown for any reason, this function has no effect (strong exception guarantee).}}
 
{{rev end}}
 
{{rev end}}
 +
 +
===Defect reports===
 +
{{dr list begin}}
 +
{{dr list item|wg=lwg|dr=2946|std=C++17|before={{tt|string_view}} overload causes ambiguity in some cases|after=avoided by making it a template}}
 +
{{dr list end}}
  
 
===Example===
 
===Example===
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{{dsc end}}
 
{{dsc end}}
  
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[[de:cpp/string/basic string/insert]]
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{{langlinks|de|es|fr|it|ja|pt|ru|zh}}
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[[es:cpp/string/basic string/insert]]
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[[fr:cpp/string/basic string/insert]]
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[[it:cpp/string/basic string/insert]]
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[[zh:cpp/string/basic string/insert]]
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Revision as of 08:16, 18 March 2018

 
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)
basic_string& insert( size_type index, const CharT* s );
 (2)
basic_string& insert( size_type index, const CharT* s, size_type count );
 (3)
basic_string& insert( size_type index, const basic_string& str );
 (4)
(5)
basic_string& insert( size_type index, const basic_string& str,
                      size_type index_str, size_type count );
 (until C++14)
basic_string& insert( size_type index, const basic_string& str,
                      size_type index_str, size_type count = npos);
 (since C++14)
(6)
iterator insert( iterator pos, CharT ch );
 (until C++11)
iterator insert( const_iterator pos, CharT ch );
 (since C++11)
(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)
(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)
iterator insert( const_iterator pos, std::initializer_list<CharT> ilist );
 (9) (since C++11)
template < class T >
basic_string& insert( size_type pos, const T& t );
 (10) (since C++17)
template < class T >

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

                      size_type index_str, size_type count = npos);
 (11) (since C++17)

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 (effectively calls Traits::length(s).
3) Inserts the first count characters from the character string pointed to by s at the position index. s can contain null characters.
4) Inserts string str at the position index
5) Inserts a string, obtained by str.substr(index_str, 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 pointed by pos
8) Inserts characters from the range [first, last) before the element pointed by pos. This overload does not participate in overload resolution if InputIt does not satisfy Template:concept.(since C++11)
9) Inserts elements from initializer list ilist before the element 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 pointed by pos, as if by insert(pos, 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 pointed by pos, the characters from the subview [index_str, index_str+count) of sv. If the requested subview lasts past the end of sv, or if count == npos, the resulting subview is [index_str, sv.size()). If index_str > 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.

Contents

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
index_str - position of the first character in the string 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
Type requirements

Template:par req concept

Return value

1-5,10-11) *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)

Exceptions

1) std::out_of_range if index > size() and std::length_error if size() + count > max_size().
2) std::out_of_range if index > size() and std::length_error if size() + Traits::length(s) > max_size().
3) std::out_of_range if index > size() and std::length_error if size() + count > max_size().
4) std::out_of_range if index > size() and std::length_error if size() + str.size() > max_size().
5) Throws exceptions on the following conditions:
a) std::out_of_range if index > size().
b) std::out_of_range if index_str > str.size().
c) std::length_error if size() + ins_count > max_size() where ins_count is the number of characters that will be inserted.
6-9) (none)
10) std::out_of_range if index > size() and std::length_error if size() + sv.size() > max_size().
11) Throws exceptions on the following conditions:
a) std::out_of_range if index > size().
b) std::out_of_range if index_str > sv.size().
c) std::length_error if size() + ins_count > max_size() where ins_count is the number of characters that will be inserted.
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

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 index_str, 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);
}

See also

 appends characters to the end
(public member function) [edit]
appends a character to the end
(public member function) [edit]
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