Introduction:

In programming, a frequency counter is a tool used to count how many times each element or character appears in a given input, such as a string or array. In this case, we’ll be focusing on counting the frequency of each character in a string. This is useful in various applications such as text analysis, pattern recognition, and compression algorithms.

Objective:

The goal of this program is to write a C++ application that takes an input string and counts how many times each character appears in the string. By the end of the program, the user will see a frequency distribution of the characters in the input string.

Program Code in C++

#include 
#include 
#include 
using namespace std;

int main() {
    string inputString;
    cout << "Enter a string: ";
    getline(cin, inputString); // Taking input string

    // Create an unordered map to store character frequencies
    unordered_map<char, int> freqCounter;

    // Loop through each character of the string
    for (char c : inputString) {
        freqCounter[c]++; // Increment the frequency count for each character
    }

    // Display the frequency of each character
    cout << "Character frequencies in the string are:" << endl;
    for (const auto& pair : freqCounter) {
        cout << pair.first << ": " << pair.second << endl;
    }

    return 0;
}

Explanation of the Program Structure:

The program starts by including the necessary libraries:

• iostream – for input/output operations.
• unordered_map – to store the characters and their frequencies efficiently.
• string – for handling the input string.

The main program performs the following steps:

1. It prompts the user to enter a string.
2. The input string is stored in the variable inputString.
3. An unordered_map called freqCounter is created to hold the frequency of each character.
4. We loop through each character in the string. For each character, we increment its count in the freqCounter.
5. After processing the string, we print the frequency of each character stored in the map.

How to Run the Program:

To run this C++ program, follow these steps:

1. Open your preferred C++ development environment (IDE) or a text editor.
2. Copy and paste the provided code into a new C++ file (for example, frequency_counter.cpp).
3. Compile the program using a C++ compiler. For example, if you’re using the command line, run: g++ frequency_counter.cpp -o frequency_counter.
4. Run the compiled program by typing ./frequency_counter (on Linux or macOS) or frequency_counter.exe (on Windows).
5. Enter a string when prompted and the program will display the frequency of each character in the string.