C++ String Exercises: Find Unique Character String

Last update on April 11 2025 12:48:14 (UTC/GMT +8 hours)

39. Check if a String Contains Only Unique Characters

Write a C++ program that checks whether a given string contains unique characters or not. Return true if the string contains unique characters otherwise false.

Test Data:
("Filename") -> 0
("abc") -> 1

Sample Solution:

C++ Code:

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

using namespace std; // Using the standard namespace

// Function to check if a string contains all unique characters
bool test(string word) {
    for (int i = 0; i < word.length() - 1; i++) { // Iterate through the characters in the string
        for (int j = i + 1; j < word.length(); j++) { // Check against subsequent characters in the string
            if (word[i] == word[j]) { // If a character repeats later in the string
                return false; // Return false, indicating the string doesn't contain all unique characters
            }
        }
    }
    return true; // Return true if no characters are repeated, indicating all characters are unique
}

int main() {
    // Test cases
    string str = "Filename"; // Define a string
    cout << "String: " << str;
    cout << "\nCheck said string contains unique characters! " << test(str) << endl; // Display if "Filename" contains all unique characters

    str = "abc"; // Define another string
    cout << "\nString: " << str;
    cout << "\nCheck said string contains unique characters! " << test(str) << endl; // Display if "abc" contains all unique characters
}

Sample Output:

String: Filename
Check said string contains unique characters! 0

String: abc
Check said string contains unique characters! 1

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to determine if a string has all unique characters by comparing each character with every other character.
• Write a C++ program that uses a boolean array to check if all characters in a string are distinct.
• Write a C++ program to check uniqueness of characters in a string without using any STL containers.
• Write a C++ program that reads a string and returns true if no character appears more than once, otherwise false.

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Previous C++ Exercise: Remove a specific character from a given string.