std::basic_string<CharT,Traits,Allocator>::assign - cppreference.com (original) (raw)

basic_string& assign( const basic_string& str );	(1)	(constexpr since C++20)
basic_string& assign( basic_string&& str ) noexcept(/* see below */);	(2)	(since C++11) (constexpr since C++20)
basic_string& assign( size_type count, CharT ch );	(3)	(constexpr since C++20)
basic_string& assign( const CharT* s, size_type count );	(4)	(constexpr since C++20)
basic_string& assign( const CharT* s );	(5)	(constexpr since C++20)
template< class SV >basic_string& assign( const SV& t );	(6)	(since C++17) (constexpr since C++20)
template< class SV > basic_string& assign( const SV& t, size_type pos, size_type count = npos);	(7)	(since C++17) (constexpr since C++20)
(8)
basic_string& assign( const basic_string& str, size_type pos, size_type count );		(until C++14)
basic_string& assign( const basic_string& str, size_type pos, size_type count = npos);		(since C++14) (constexpr since C++20)
template< class InputIt >basic_string& assign( InputIt first, InputIt last );	(9)	(constexpr since C++20)
basic_string& assign( std::initializer_list<CharT> ilist );	(10)	(since C++11) (constexpr since C++20)

Replaces the contents of the string.

Equivalent to return *this = str;.
Equivalent to return *this = std::move(str);.
Replaces the contents with count copies of character ch.

Equivalent to clear(); resize(n, c); return *this;.

Replaces the contents with copies of the characters in the range [s, s + count).

If [s, s + count) is not a valid range, the behavior is undefined.

Equivalent to return assign(s, Traits::length(s));.

6,7) Replaces the contents with characters in a string view sv constructed from t.

If only t is provided, replaces the contents with all characters in sv.
If pos is also provided:
- If count is npos, replaces the contents with all characters in sv starting from pos.
- Otherwise, replaces the contents with the std::min(count, sv.size() - pos) characters in sv starting from pos.

Equivalent to std::basic_string_view<CharT, Traits> sv = t;
return assign(sv.data(), sv.size());.
Equivalent to std::basic_string_view<CharT, Traits> sv = t;
return assign(sv.substr(pos, count));.
Replaces the contents with characters in str.

If count is npos, replaces the contents with all characters in str starting from pos.
Otherwise, replaces the contents with the std::min(count, str.size() - pos) characters in str starting from pos.

Equivalent to return assign(basic_string(first, last, get_allocator()));.

This overload participates in overload resolution only if InputIt satisfies the requirements of LegacyInputIterator.	(since C++11)

Equivalent to return assign(ilist.begin(), ilist.size());.

[edit] Parameters

str	-	string to be used as source to initialize the characters with
count	-	size of the resulting string
ch	-	value to initialize characters of the string with
s	-	pointer to a character string to use as source to initialize the string with
t	-	object (convertible to std::basic_string_view) to initialize the characters of the string with
pos	-	index of the first character to take
first, last	-	range to copy the characters from
ilist	-	std::initializer_list to initialize the characters of the string with

[edit] Return value

*this

[edit] Exceptions

If the operation would cause size() to exceed max_size(), throws std::length_error.

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

[edit] Example

#include #include #include int main() { std::string s; // assign(size_type count, CharT ch) s.assign(4, '='); std::cout << s << '\n'; // "====" std::string const c("Exemplary"); // assign(const basic_string& str) s.assign(c); std::cout << c << " == " << s << '\n'; // "Exemplary == Exemplary" // assign(const basic_string& str, size_type pos, size_type count) s.assign(c, 0, c.length() - 1); std::cout << s << '\n'; // "Exemplar"; // assign(basic_string&& str) s.assign(std::string("C++ by ") + "example"); std::cout << s << '\n'; // "C++ by example" // assign(const CharT* s, size_type count) s.assign("C-style string", 7); std::cout << s << '\n'; // "C-style" // assign(const CharT* s) s.assign("C-style\0string"); std::cout << s << '\n'; // "C-style" char mutable_c_str[] = "C-style string"; // assign(InputIt first, InputIt last) s.assign(std::begin(mutable_c_str), std::end(mutable_c_str) - 1); std::cout << s << '\n'; // "C-style string" // assign(std::initializer_list ilist) s.assign({'C', '-', 's', 't', 'y', 'l', 'e'}); std::cout << s << '\n'; // "C-style" }

Output:

==== Exemplary == Exemplary Exemplar C++ by example C-style C-style C-style string C-style

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.