﻿ C++ - Count number of duplicate characters in a given string

C++ String Exercises: Count number of duplicate characters in a given string

C++ String: Exercise-24 with Solution

Write a C++ program to count the number of duplicate characters in a given string.

Note: Spaces are included and characters are case sensitive

Sample Data:
(“APple”) -> 0
(“Remove all special characters from a given string”) -> 31
(“Total number of unique characters of the said two strings.”) ->36

Sample Solution-1:

C++ Code:

``````#include <bits/stdc++.h> // Includes all standard libraries

using namespace std; // Using the standard namespace

int test(std::string text) { // Function to count duplicate characters in a string
int ctr = 0; // Counter to keep track of duplicate characters

sort(text.begin(), text.end()); // Sorts characters in the string alphabetically

// Iterate through each character in the string
for (int i = 0; i < text.size(); i++) {
if (text[i] == text[i + 1]) { // If the current character is the same as the next one
ctr = ctr + 1; // Increment the counter for duplicate characters
}
}
return ctr; // Return the count of duplicate characters
}

int main() {
//string text = "APple";
//string text = "Remove all special characters from a given string.";
string text = "Total number of unique characters of the said two strings."; // Declare and initialize a string

cout << "Original String:\n";
cout << text; // Output the original string
cout << "\n\nNumber of duplicate characters in the said string: ";
cout << test(text) << endl; // Call function test and output the number of duplicate characters in the string
}
``````

Sample Output:

```Original String:
Total number of unique characters of the said two strings.

Number of duplicate characters in the said string: 36
```

Flowchart:

Sample Solution-2:

C++ Code:

``````#include <bits/stdc++.h> // Includes all standard libraries

using namespace std; // Using the standard namespace

int test(std::string text) { // Function to count duplicate characters in a string
// Creating a set from the characters in the input string, which automatically filters out duplicates
std::set<char> set(text.begin(), text.end());
int ctr = text.length() - set.size(); // Calculating the difference to get the count of duplicates
return ctr; // Return the count of duplicate characters
}

int main() {
string text = "APple"; // Declare and initialize a string
//string text = "Remove all special characters from a given string.";
//string text = "Total number of unique characters of the said two strings.";
cout << "Original String:\n";
cout << text; // Output the original string
cout << "\n\nNumber of duplicate characters in the said string: ";
cout << test(text) << endl; // Call function test and output the number of duplicate characters in the string
}
``````

Sample Output:

```Original String:
APple

Number of duplicate characters in the said string: 0
```

Flowchart:

C++ Code Editor: