multimap::operator= in C++ STL

multimap::operator= is used to assign new contents to the container by replacing the existing contents. It also modifies the size according to the new contents. 

Syntax:-

multimap1 = (multimap2)

Parameters :
Another container of the same type.

Result :
Assign the contents of the container passed as 
parameter to the container written on left 
side of the operator.

Examples:

Input  :  multimap1 = { ('a', 1), ('b', 2), ('c', 3)}
          multimap2 = { ('d', 4), ('e', 5), ('f', 6)}
          multimap1 = multimap2;
Output :  multimap1 
d 4
e 5
f 6

Input  :  multimap1 = { ('abc', 1), ('bca', 2), ('cab', 3)}
          multimap2 = { ('def', 4), ('efd', 5), ('fde', 6)}
          multimap1 = multimap2;
Output :  multimap1 
def 4
efd 5
fde 6

Errors and Exceptions 

1. If the containers are of different types, an error is thrown. 
2. It has a basic no exception throw guarantee otherwise. 

// CPP Program to illustrate working of 
// multimap::operator= 
#include <iostream> 
#include <map> 
using namespace std; 

int main() 
{ 
    // initialise multimap 
    multimap<char, int> m1; 
    multimap<char, int> m2; 

    // iterator for iterate all element of multimap 
    multimap<char, int>::iterator iter; 

    // multimap1 data 
    m1.insert(make_pair('a', 1)); 
    m1.insert(make_pair('b', 2)); 
    m1.insert(make_pair('c', 3)); 

    // multimap2 data 
    m2.insert(make_pair('d', 4)); 
    m2.insert(make_pair('e', 5)); 
    m2.insert(make_pair('f', 6)); 

    // operator= 
    m1 = m2; 

    // multimap1 data 
    cout << "MultiMap 1 data" << "\n"; 
    for (iter = m1.begin(); iter != m1.end(); iter++) 
        cout << (*iter).first << " " << (*iter).second << "\n"; 
} 

Output:-

MultiMap 1 data
d 4
e 5
f 6

Time Complexity : O(N)

devanshuagarwal

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Article Tags :

• Misc
• C++
• STL
• cpp-multimap

Practice Tags :

• CPP
• Misc
• STL