C#: Count the number of times the string 'aa' appears in a given string and assume that 'aaa' contains two 'aa'

Last update on June 25 2025 13:03:04 (UTC/GMT +8 hours)

Count 'aa' in String

Write a C# Sharp program to count the number of times the string "aa" appears in a given string and assume that "aaa" contains two "aa".

Visual Presentation:

Sample Solution:-

C# Sharp Code:

using System;

// Namespace declaration
namespace exercises
{
    // Class declaration
    class Program
    {
        // Main method - entry point of the program
        static void Main(string[] args)
        {
            // Displaying the output of the 'test' method with different string inputs
            Console.WriteLine(test("bbaaccaag"));  // Output: 2
            Console.WriteLine(test("jjkiaaasew"));  // Output: 1
            Console.WriteLine(test("JSaaakoiaa"));  // Output: 2
            Console.ReadLine();  // Keeping the console window open
        }

        // Method to count the occurrences of the substring "aa" in the given string 's'
        public static int test(string s)
        {
            int ctr_aa = 0;  // Counter to store the number of occurrences of "aa" in the string

            // Loop through the string characters up to the second-to-last character
            for (int i = 0; i < s.Length - 1; i++)
            {
                // Check if the current and next character form the substring "aa"
                if (s.Substring(i, 2) == "aa")
                {
                    ctr_aa++;  // Increment the counter if "aa" is found
                }
            }

            return ctr_aa;  // Return the total count of occurrences of "aa" in the given string
        }
    }
}

Sample Output:

2
2
3

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C# program to count the number of overlapping "aa" patterns in a string.
• Write a C# program to count how many "aa" pairs are surrounded by digits in a given string.
• Write a C# program to count instances of "aa" where the second 'a' is not the last character in the string.
• Write a C# program to count all "aa" patterns that are not part of an "aaa" pattern.

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