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  1. #include <iostream>
  2. #include<map>
  3. #include<iterator>
  4. #include<utility>
  5. using namespace std;
  6.  
  7. void printMap(map<string,int> &fm){
  8. 	cout << fm.size() << endl;
  9. 	//map<string,int>::iterator it;
  10. 	for(auto it = fm.begin();it != fm.end();++it){
  11. 		//cout << (*it).first << "-" << (*it).second << endl;
  12. 		cout << it->first << "-" << it->second << endl;
  13. 	}
  14. }
  15. int main() {
  16. 	//basic initialization.
  17. 	map<string,int> m1;
  18. 	m1["date"] = 22; //O(log(n));n = current size.
  19. 	m1["month"] = 05;
  20. 	m1["year"] = 2004;
  21. 	printMap(m1);
  22.  
  23. 	//initializing a map using pair,using insert():
  24. 	map<string,int> m2;
  25. 	m2.insert(make_pair("date",22));
  26. 	m2.insert({"month",05});
  27. 	printMap(m2);
  28. 	m2["day"]; //inserts an empty string to "day" key.
  29. 	printMap(m2);
  30.  
  31. 	//find(key):return the iterator for a specific key in the map.
  32. 	//if the key doesnt exist, it will return the iterator for end().
  33. 	auto it2 = m2.find("date");
  34. 	cout << (*it2).second << endl;
  35. 	auto it3 = m2.find("month");
  36. 	if(it3 == m2.end())
  37. 		cout << "no such key\n";
  38. 	else
  39. 		cout << it3->second << endl;
  40. 	return 0;
  41. }
Success #stdin #stdout 0s 5284KB
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stdin
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Standard input is empty
stdout
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3
date-22
month-5
year-2004
2
date-22
month-5
3
date-22
day-0
month-5
22
5
https://ideone.com/TzqFtD
language:
C++14 (gcc 8.3)
created:
6 days ago
visibility:
public

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