#include<iostream>
#include<string>
#include<map>
using namespace std;

// non-member template function to print the map
template <class t1, class t2>
void printMap(map<t1, t2> mp)
{
	for (class map<t1, t2> :: iterator it = mp.begin();it != mp.end(); it++)
		cout << (it -> first) << " " << (it -> second) << endl;
	cout << endl;
}

int main()
{
	map<int, int> mp;
	map<string, pair<int, int>> mp2;
	map<string, int> mp3;

	// manipulating mp, there are several ways in which you can add elements
	// to the map ...
	mp[100] = 2; // {key = 100, value = 2} // 1
	mp.insert(pair<int, int>(150, -3)); // 2
	printMap(mp);
	
	mp.insert(make_pair(50, 3)); // 3
	printMap(mp);

	mp[100] = -13; // keys in the map should be distinct !!!, thus the value of the key
	// will be different
	printMap(mp);

	cout <<  " " << mp.size() << " " << mp.max_size() << endl;

	mp.erase(mp.begin(), mp.find(150)); // will erase all the keys and values upto key 150
	// mp.erase(50); // will erase the key and the value of the key 50
	printMap(mp);
	

	mp2["Adeeb"] = make_pair(4, 2); // can alos be written as: mp2.insert(make_pair("Adeeb", make_pair(4,2)));
	mp2["Abcd"] = make_pair(5, 1);
	for (map<string, pair<int, int>>::iterator it = mp2.begin();
			it != mp2.end(); it++)
		cout << (it -> first) << " " << (it -> second).first << " " << (it -> second).second << endl;

	cout << "\n *** mp3 ***\n";
	mp3["Sami"] = 15;
	mp3["Ahmad"] = 189;
	mp3["Yazeed"] = 2;
	printMap(mp3);

	system("pause");

}
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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}