Mega Code Archive
Duplicate keys are not allowed in a map
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#include <iostream>
#include <string>
#include <map>
#include <utility>
using namespace std;
void show(const char *msg, map<string, string> mp);
int main() {
map<string, string> phonemap;
phonemap["A"] = "444-555-1234";
phonemap["B"] = "555-555-6576";
phonemap["C"] = "555-555-9843";
show("Here is the original map: ", phonemap);
cout << endl;
// Now, change the phone number for Ken.
phonemap["B"] = "555 555-5555";
cout << "New number for Ken: " << phonemap["Ken"] << "\n\n";
// Create a pair object that will contain the result of a call to insert().
pair<map<string, string>::iterator, bool> result;
// Duplicate keys are not allowed, as the following proves.
result = phonemap.insert(pair<string, string>("B", "555-1010"));
if(result.second)
cout << "Duplicate added! Error!";
else
cout << "Duplicate not allowed.\n";
show("phonemap after attempt to add duplicate 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;
}
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