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  1. //
  2. //  main.cpp
  3. //  Map and Unordered Map (STL)
  4. //
  5. //  Created by Himanshu on 23/03/22.
  6. //
  7.  
  8. #include <iostream>
  9. #include <map>
  10. #include <unordered_map>
  11. #include <string>
  12. using namespace std;
  13.  
  14. void printUnorderedMap (unordered_map<string, int> myMap) {
  15.     for (auto& it: myMap) {
  16.         cout<<(it.first)<<": "<<(it.second)<<" ";
  17.     }
  18.     cout<<endl;
  19. }
  20.  
  21. void printMap (map<string, int> myMap) {
  22.     for (auto& it: myMap) {
  23.         cout<<(it.first)<<": "<<(it.second)<<" ";
  24.     }
  25.     cout<<endl;
  26. }
  27.  
  28. int main () {
  29.  
  30.     unordered_map<string, int> initUnorderedMap = { {"beta", 2}, {"gamma", 3}, {"alpha", 1} };
  31.     map<string, int> initMap = { {"beta", 2}, {"gamma", 3}, {"alpha", 1} };
  32.  
  33.     unordered_map<string, int> myUnorderedMap;
  34.     map<string, int> myMap;
  35.  
  36.     map<string, int>::iterator it;
  37.  
  38.     //Iterating over 'unordered_map'
  39.     cout<<"initUnorderedMap elements:"<<endl;
  40.     printUnorderedMap(initUnorderedMap);
  41.  
  42.     //Iterating over 'map'
  43.     cout<<endl<<"initMap elements:"<<endl;
  44.     printMap(initMap);
  45.  
  46.     cout<<"Elements in the initMap (map) container are kept sorted based on their key values"<<endl;
  47.  
  48.     initUnorderedMap.clear();
  49.     //size of unordered_map after clear
  50.     cout<<endl<<"Size of unordered_map after clear: "<<initUnorderedMap.size()<<endl;
  51.  
  52.     initMap.clear();
  53.     //size of map after clear
  54.     cout<<endl<<"Size of map after clear: "<<initMap.size()<<endl;
  55.  
  56.     myUnorderedMap.insert({"first", 30});
  57.     myUnorderedMap["second"] = 20;
  58.     myUnorderedMap["third"] = 10;
  59.  
  60.     myMap.insert({"first", 10});
  61.     myMap["second"] = 20;
  62.     myMap["third"] = 30;
  63.  
  64.     //Iterating over 'myUnorderedMap'
  65.     cout<<endl<<"myUnorderedMap elements:"<<endl;
  66.     printUnorderedMap(myUnorderedMap);
  67.  
  68.     //Iterating over 'myMap'
  69.     cout<<endl<<"myMap elements:"<<endl;
  70.     printMap(myMap);
  71.  
  72.     //Iterating over 'myUnorderedMap' after erase
  73.     myUnorderedMap.erase("second");
  74.     cout<<endl<<"myUnorderedMap elements after erase 'second': "<<endl;
  75.     printUnorderedMap(myUnorderedMap);
  76.  
  77.     //Iterating over 'myMap' after erase
  78.     myMap.erase(myMap.begin());
  79.     cout<<endl<<"myMap elements after erase myMap.begin(): "<<endl;
  80.     printMap(myMap);
  81.     cout<<endl<<"Find operation on map and unordered_map:"<<endl;
  82.  
  83.     if (myUnorderedMap.find("second") != myUnorderedMap.end()) {
  84.         cout<<"key 'second' is present in myUnorderedMap"<<endl;
  85.     } else {
  86.         cout<<"key 'second' is not present in myUnorderedMap"<<endl;
  87.     }
  88.  
  89.     if (myMap.find("second") != myMap.end()) {
  90.         cout<<"key 'second' is present in myMap"<<endl;
  91.     } else {
  92.         cout<<"key 'second' is not present in myMap"<<endl;
  93.     }
  94.  
  95.     myMap.clear();
  96.  
  97.     myMap["a"] = 1;
  98.     myMap["b"] = 2;
  99.     myMap["c"] = 3;
  100.     myMap["d"] = 4;
  101.     myMap["e"] = 5;
  102.     myMap["f"] = 6;
  103.     myMap["g"] = 7;
  104.     myMap["h"] = 8;
  105.  
  106.     //Iterating over 'myMap'
  107.     cout<<endl<<"myMap new elements after clear:"<<endl;
  108.     printMap(myMap);
  109.  
  110.     //Iterating over 'myMap' after erase on a range
  111.     myMap.erase(myMap.find("f"), myMap.end());
  112.     cout<<endl<<"myMap elements after erasing a range of elements:"<<endl;
  113.     printMap(myMap);
  114.  
  115.     //Upper bound of "c" in myMap
  116.     cout<<endl<<"(Upper bound method is available for map but not for unordered_map) Upper bound of 'c' in myMap: ";
  117.     cout<<((myMap.upper_bound("c"))->first)<<": "<<((myMap.upper_bound("c"))->second)<<endl;
  118.  
  119.     //Lower bound of "c" in myMap
  120.     it  = myMap.lower_bound("c");
  121.     cout<<endl<<"(Lower bound method is available for map but not for unordered_map) Lower bound of 'c' in myMap: ";
  122.     cout<<it->first<<": "<<it->second<<endl;
  123.  
  124.     return 0;
  125. }
Success #stdin #stdout 0.01s 5372KB
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stdin
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Standard input is empty
stdout
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initUnorderedMap elements:
gamma: 3 alpha: 1 beta: 2 

initMap elements:
alpha: 1 beta: 2 gamma: 3 
Elements in the initMap (map) container are kept sorted based on their key values

Size of unordered_map after clear: 0

Size of map after clear: 0

myUnorderedMap elements:
third: 10 first: 30 second: 20 

myMap elements:
first: 10 second: 20 third: 30 

myUnorderedMap elements after erase 'second': 
third: 10 first: 30 

myMap elements after erase myMap.begin(): 
second: 20 third: 30 

Find operation on map and unordered_map:
key 'second' is not present in myUnorderedMap
key 'second' is present in myMap

myMap new elements after clear:
a: 1 b: 2 c: 3 d: 4 e: 5 f: 6 g: 7 h: 8 

myMap elements after erasing a range of elements:
a: 1 b: 2 c: 3 d: 4 e: 5 

(Upper bound method is available for map but not for unordered_map) Upper bound of 'c' in myMap: d: 4

(Lower bound method is available for map but not for unordered_map) Lower bound of 'c' in myMap: c: 3
https://ideone.com/j3hP7V
language:
C++ 4.3.2 (gcc-4.3.2)
created:
1 year ago
visibility:
secret

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