Creates a map that works as a phone directory, in which a person's name is the key and the phone number is the value. - C++ STL

C++ examples for STL:map

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Description

Creates a map that works as a phone directory, in which a person's name is the key and the phone number is the value.

Demo Code

#include <iostream>
#include <string>
#include <map>
#include <utility>
using namespace std;
void show(const char *msg, map<string, string> mp);
int main() {//from   w w  w  .j a v  a2 s  . c o  m
   map<string, string> phonemap;
   // Insert elements by using operator[].
   phonemap["Tom"] = "555-1234";
   phonemap["Jane"] = "111 555-6543";
   phonemap["Ken"] = "222 555-1234";
   show("Here is the original map: ", phonemap);
   cout << endl;
   // Now, change the phone number for Ken.
   phonemap["Ken"] = "415 997-8888";
   cout << "New number for Ken: " << phonemap["Ken"] << "\n\n";
   // Use find() to find a number.
   map<string, string>::iterator itr;
   itr = phonemap.find("Jane");
   if(itr != phonemap.end())
      cout << "Number for Jane is " << itr->second << "\n\n";
   // Cycle through the map in the reverse direction.
   map<string, string>::reverse_iterator ritr;
   cout << "Display phonemap in reverse order:\n";
   for(ritr = phonemap.rbegin(); ritr != phonemap.rend(); ++ritr)
      cout << "  " << ritr->first << ": " << ritr->second << endl;
   cout << endl;
   // Create a pair object that will contain the result
   // of a call to insert().
   pair<map<string, string>::iterator, bool> result;
   // Use insert() to add an entry.
   result = phonemap.insert(pair<string, string>("Jay", "555-9999"));
   if(result.second) cout << "Jay added.\n";
   show("phonemap after adding Jay: ", phonemap);
   // Duplicate keys are not allowed, as the following proves.
   result = phonemap.insert(pair<string, string>("Jay", "555-1010"));
   if(result.second) cout << "Duplicate Jay added! Error!";
   else cout << "Duplicate Jay not allowed.\n";
   show("phonemap after attempt to add duplicate Jay key: ", phonemap);
   return 0;
}
// Display the contents of a map<string, string> by using
// an iterator.
void show(const char *msg, map<string, string> mp) {
   map<string, string>::iterator itr;
   cout << msg << endl;
   for(itr=mp.begin(); itr != mp.end(); ++itr)
      cout << "  " << itr->first << ": " << itr->second << endl;
   cout << endl;
}

Result


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