hash_map::operator(STL/CLR)

[アーティクル]
06/05/2017

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The latest version of this topic can be found at hash_map::operator(STL/CLR).

Maps a key to its associated mapped value.

Syntax

mapped_type operator[](key_type key);

Parameters

key
Key value to search for.

Remarks

The member functions endeavors to find an element with equivalent ordering to key. If it finds one, it returns the associated mapped value; otherwise, it inserts value_type(``key``, mapped_type()) and returns the associated (default) mapped value. You use it to look up a mapped value given its associated key, or to ensure that an entry exists for the key if none is found.

Example

// cliext_hash_map_operator_sub.cpp   
// compile with: /clr   
#include <cliext/hash_map>   
  
typedef cliext::hash_map<wchar_t, int> Myhash_map;   
int main()   
    {   
    Myhash_map c1;   
    c1.insert(Myhash_map::make_value(L'a', 1));   
    c1.insert(Myhash_map::make_value(L'b', 2));   
    c1.insert(Myhash_map::make_value(L'c', 3));   
  
// display contents " [a 1] [b 2] [c 3]"   
    for each (Myhash_map::value_type elem in c1)   
        System::Console::Write(" [{0} {1}]", elem->first, elem->second);   
    System::Console::WriteLine();   
  
    System::Console::WriteLine("c1[{0}] = {1}",   
        L'A', c1[L'A']);   
    System::Console::WriteLine("c1[{0}] = {1}",   
        L'b', c1[L'b']);   
  
// redisplay altered contents   
    for each (Myhash_map::value_type elem in c1)   
        System::Console::Write(" [{0} {1}]", elem->first, elem->second);   
    System::Console::WriteLine();   
  
// alter mapped values and redisplay   
    c1[L'A'] = 10;   
    c1[L'c'] = 13;   
    for each (Myhash_map::value_type elem in c1)   
        System::Console::Write(" [{0} {1}]", elem->first, elem->second);   
    System::Console::WriteLine();   
    return (0);   
    }

 [a 1] [b 2] [c 3]  
c1[A] = 0  
c1[b] = 2  
 [a 1] [A 0] [b 2] [c 3]  
 [a 1] [A 10] [b 2] [c 13]

Requirements

Header: <cliext/hash_map>

Namespace: cliext

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