C++ Program to Find the Frequency of Characters in a String

In this example, frequency of occurrence of a character is checked for both (String object and C-style string).

To understand this example, you should have the knowledge of following C++ programming topics:

In this example, frequency of characters in a string object is computed.

To do this, size() function is used to find the length of a string object. Then, the for loop is iterated until the end of the string.

In each iteration, occurrence of character is checked and if found, the value of count is incremented by 1.


Example 1: Find Frequency of Characters of a String Object

#include <iostream>
using namespace std;

int main()
{
    string str = "C++ Programming is awesome";
    char checkCharacter = 'a';
    int count = 0;

    for (int i = 0; i < str.size(); i++)
    {
        if (str[i] ==  checkCharacter)
        {
            ++ count;
        }
    }

    cout << "Number of " << checkCharacter << " = " << count;

    return 0;
}

Output

Number of a = 2

In the example below, loop is iterated until the null character '\0' is encountered. Null character indicates the end of the string.

In each iteration, the occurrence of the character is checked.


Example 2: Find Frequency of Characters in a C-style String

#include <iostream>

using namespace std;
int main()
{
   char c[] = "C++ programming is not easy.", check = 'm';
   int count = 0;

   for(int i = 0; c[i] != '\0'; ++i)
   {
       if(check == c[i])
           ++count;
   }
   cout << "Frequency of " << check <<  " = " << count;
   return 0;
}

Output

Number of m = 2