#include<iostream>
#include<algorithm>
#include <chrono> 
using namespace std;
using namespace std::chrono; 
void display(int *array, int size) {
   for(int i = 1; i<=size; i++)
      cout << array[i] << " ";
   cout << endl;
}
int getMax(int array[], int size) {
   int max = array[1];
   for(int i = 2; i<=size; i++) {
      if(array[i] > max)
         max = array[i];
   }
   return max; //the max element from the array
}
void countSort(int *array, int size) {
   int output[size+1];
   int max = getMax(array, size);
   int count[max+1];     //create count array (max+1 number of elements)
   for(int i = 0; i<=max; i++)
      count[i] = 0;     //initialize count array to all zero
   for(int i = 1; i <=size; i++)
      count[array[i]]++;     //increase number count in count array.
   for(int i = 1; i<=max; i++)
      count[i] += count[i-1];     //find cumulative frequency
   for(int i = size; i>=1; i--) {
      output[count[array[i]]] = array[i];
      count[array[i]] -= 1; //decrease count for same numbers
   }
   for(int i = 1; i<=size; i++) {
      array[i] = output[i]; //store output array to main array
   }
}
int main() {
   int n;
   cout << "Enter the number of elements: ";
   cin >> n;
   int arr[n+1];       //create an array with given number of elements
   for(int i = 1; i<=n; i++) {
      arr[i]=rand() % 10;
   }
   cout << "Array before Sorting: ";
   display(arr, n);
   auto start = high_resolution_clock::now(); 
   countSort(arr, n);
   auto stop = high_resolution_clock::now();
   cout << "Array after Sorting: ";
   display(arr, n);
   auto duration = duration_cast<microseconds>(stop - start); 
   cout << "Time taken by function: "<< duration.count() << " microseconds" << endl; 
}
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C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

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
}