std::basic_string::append - cppreference.com

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# std::basic_string::append

From cppreference.com
< cpp‎ | string‎ | basic string

basic_string& append( size_type count, CharT ch ); | (1) |
basic_string& append( const basic_string& str ); | (2) |
| (3) |
basic_string& append( const basic_string& str, size_type pos, size_type count ); |  | (until C++14)
basic_string& append( const basic_string& str, size_type pos, size_type count = npos); |  | (since C++14)
basic_string& append( const CharT* s, size_type count ); | (4) |
basic_string& append( const CharT* s ); | (5) |
template< class InputIt > basic_string& append( InputIt first, InputIt last ); | (6) |
basic_string& append( std::initializer_list<CharT> ilist ); | (7) | (since C++11)

Appends additional characters to the string.

1) Appends `count` copies of character `ch`

2) Appends string `str`

3) Appends a substring `[pos, pos+count)` of `str`. If the requested substring lasts past the end of the string, or if count == npos, the appended substring is `[pos, size())`. If pos >= str.size(), std::out_of_range is thrown.

4) Appends the first `count` characters of character string pointed to by `s`. `s` can contain null characters.

5) Appends the null-terminated character string pointed to by `s`. The length of the string is determined by the first null character.

6) Appends characters in the range `[first, last)`. This overload does not participate in overload resolution if `InputIt` does not satisfy `InputIterator`. (since C++11)

7) Appends characters in the initializer list `ilist`.

### [edit] Parameters

count | - | number of characters to append
ch | - | character value to append
first, last | - | range of characters to append
str | - | string to append
s | - | pointer to the character string to append
ilist | - | initializer list with the characters to append
Type requirements
- `InputIt` must meet the requirements of `InputIterator`.

### [edit] Return value

*this

### [edit] Complexity

1) linear in `count`

2) linear in size of `str`

3-4) linear in `count`

5) linear in size of `s`

6) linear in distance between `first` and `last`

7) linear in size of `ilist`

### [edit] Exceptions

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

If the operation would result in `size() > max_size()`, throws std::length_error.

### [edit] Example

Run this code

    #include <string>
    #include <iostream>

    int main() {
        std::basic_string<char> str = "string";
        const char* cptr = "C-string";
        const char carr[] = "Two and one";

        std::string output;

        // 1) Repeat a char
        output.append(3, '*');
        std::cout << "1) " << output << "\n";

        //  2) Append a whole string
        output.append(str);
        std::cout << "2) " << output << "\n";

        // 3) Append part of a string (last 3 letters, in this case)
        output.append(str, 3, 3);
        std::cout << "3) " << output << "\n";

        // 4) Append part of a C-string
        // Notice, because `append` returns *this, we can chain calls together
        output.append(1, ' ').append(carr, 4);
        std::cout << "4) " << output << "\n";

        // 5) Append a whole C-string
        output.append(cptr);
        std::cout << "5) " << output << "\n";

        // 6) Append range
        output.append(&carr[3], std::end(carr));
        std::cout << "6) " << output << "\n";

        // 7) Append initializer list
        output.append({ ' ', 'l', 'i', 's', 't' });
        std::cout << "7) " << output << "\n";
    }

Output:

    1) ***
    2) ***string
    3) ***stringing
    4) ***stringing Two
    5) ***stringing Two C-string
    6) ***stringing Two C-string and one
    7) ***stringing Two C-string and one list

### [edit] See also

operator+= | appends characters to the end (public member function) [edit]

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