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Difference between revisions of "Template:cpp/container/assign"

From cppreference.com
m (→‎Example: ~ assignment of a container of other type)
m (→‎Example: + `const` to show that the source won't be modified)
Line 86: Line 86:
 
     print_{{{1}}}();
 
     print_{{{1}}}();
 
      
 
      
−
     std::string extra(6, 'b');
+
     const std::string extra(6, 'b');
 
     characters.assign(extra.begin(), extra.end());
 
     characters.assign(extra.begin(), extra.end());
 
     print_{{{1}}}();
 
     print_{{{1}}}();

Revision as of 00:37, 22 January 2021

 
C++
 
Containers library
 
void assign( size_type count, const T& value );
 (1) (since {std})
template< class InputIt >
void assign( InputIt first, InputIt last );
 (2) (since {std})
void assign( std::initializer_list<T> ilist );
 (3) (since C++11)

Replaces the contents of the container.

1) Replaces the contents with count copies of value value
2) Replaces the contents with copies of those in the range [first, last). The behavior is undefined if either argument is an iterator into *this.

This overload has the same effect as overload (1) if InputIt is an integral type.

(until C++11)

This overload participates in overload resolution only if InputIt satisfies LegacyInputIterator.

(since C++11)
3) Replaces the contents with the elements from the initializer list ilist.

All iterators, pointers and references to the elements of the container are invalidated.

Contents

Parameters

count - the new size of the container
value - the value to initialize elements of the container with
first, last - the range to copy the elements from
ilist - initializer list to copy the values from

Complexity

1) Linear in count
2) Linear in distance between first and last
3) Linear in ilist.size()

Example

The following code uses assign to add several characters to a std::{{{1}}}<char>:

Run this code
#include <{{{1}}}>
#include <iostream>
#include <string>
 
int main()
{
    std::{{{1}}}<char> characters;
 
    auto print_{{{1}}} = [&](){
        for (char c : characters)
            std::cout << c << ' ';
        std::cout << '\n';  
    };
 
    characters.assign(5, 'a');
    print_{{{1}}}();
 
    const std::string extra(6, 'b');
    characters.assign(extra.begin(), extra.end());
    print_{{{1}}}();
 
    characters.assign({'C', '+', '+', '1', '1'});
    print_{{{1}}}();
}

Output: 

a a a a a 
b b b b b b 
C + + 1 1

See also

 constructs the
(public member function of std::{{{1}}}) [edit]
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