frequency of a substring in a string c++

To find the frequency of a substring in a string in C++, you can follow these steps:

Initialize a counter variable to 0. This variable will keep track of the frequency of the substring.
Use a loop to iterate through the string. The loop will start from 0 and end at the length of the string minus the length of the substring. This ensures that the loop doesn't go beyond the end of the string.
Inside the loop, use the substr function to extract a substring from the original string. The substr function takes two parameters: the starting index and the length of the substring. The starting index will be the loop variable, and the length will be the length of the substring.
Check if the extracted substring is equal to the desired substring. You can use the == operator to compare the two strings.
If the extracted substring is equal to the desired substring, increment the counter variable by 1.
After the loop is finished, the counter variable will contain the frequency of the substring in the string.

Here's a code example that demonstrates this approach:

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello, Hello, Hello, World!";
    std::string substring = "Hello";

    int frequency = 0;
    for (size_t i = 0; i <= str.length() - substring.length(); i++) {
        std::string extracted = str.substr(i, substring.length());
        if (extracted == substring) {
            frequency++;
        }
    }

    std::cout << "Frequency of substring: " << frequency << std::endl;

    return 0;
}

In this example, the string "Hello, Hello, Hello, World!" is searched for the substring "Hello". The frequency of the substring is then printed to the console.