C++ Vector Exercises: First string contains all letters from second string

Last update on August 16 2025 13:00:57 (UTC/GMT +8 hours)

5. Verify Letters of Second String in First String

Write a C++ program to verify that all of the letters in the second string appear in the first string as well. Return true otherwise false.

Sample Data:
({"Python", "Py"}) -> 1
({"CPP", "C++"}) ->.0

Sample Solution-1:

C++ Code:

#include <iostream>  // Including the Input/Output Stream Library
#include <vector>    // Including the Vector Library for using vectors

using namespace std; // Using the Standard Namespace

// Function to check if all characters in the second string are present in the first string
string test(vector<string> strs) {
    for (auto ch : strs.at(1)) { // Iterating through each character in the second string
        // Checking if the uppercase or lowercase form of the character exists in the first string
        if (strs.at(0).find(toupper(ch)) == string::npos && strs.at(0).find(tolower(ch)) == string::npos)
            return "false"; // If a character is not found in the first string, return "false"
    }
    return "true"; // If all characters are found in the first string, return "true"
}

// Main function
int main() {
    vector<string> strs = {"Python", "Py"}; // Initializing a vector of strings

    cout << "Original String elements: ";
    for (string c : strs)
        cout << c << " "; // Printing the original elements of the vector

    cout << "\nCheck - First string contains all letters from second string: ";
    string result = test(strs); // Calling the test function to check character presence in the strings
    cout << result << " "; // Printing the result ("true" or "false")
}

Sample Output:

Original String elements: Python Py 
Check - First string contains all letters from second string: true

Flowchart:

Sample Solution-2:

C++ Code:

#include <iostream>  // Including the Input/Output Stream Library
#include <vector>    // Including the Vector Library for using vectors

using namespace std; // Using the Standard Namespace

// Function to check if all characters in the second string are present in the first string
string test(vector<string> strs) {
    // Convert all characters in the first string to uppercase
    for (char &ch : strs.at(0)) 
        ch = toupper(ch);

    // Convert all characters in the second string to uppercase and check if each character exists in the first string
    for (char &ch : strs.at(1)) {
        ch = toupper(ch); // Convert the character to uppercase
        if (strs.at(0).find(ch) == std::string::npos) // Check if the character is not found in the first string
            return "false"; // If a character is not found in the first string, return "false"
    }
    return "true"; // If all characters are found in the first string, return "true"
}

// Main function
int main() {
    // vector<string> strs = {"Python", "Py"};
    vector<string> strs = {"CPP", "C++"}; // Initializing a vector of strings

    cout << "Original String elements: ";
    for (string c : strs)
        cout << c << " "; // Printing the original elements of the vector

    cout << "\nCheck - First string contains all letters from second string: ";
    string result = test(strs); // Calling the test function to check character presence in the strings
    cout << result << " "; // Printing the result ("true" or "false")
}

Sample Output:

Original String elements: CPP C++ 
Check - First string contains all letters from second string: false

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program that checks if every character from a second string is present in a first string, using a frequency array for letters.
Write a C++ program to determine if the characters in the second string form a subsequence of the first string, preserving order.
Write a C++ program that uses a hash set to verify that all letters of the second string appear in the first string regardless of order.
Write a C++ program to compare two strings and return true if the first string contains all the characters (case-sensitive) of the second string.

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