C++ String Exercises: Check first string contains letters from the second

Last update on April 11 2025 12:48:17 (UTC/GMT +8 hours)

33. Check if Letters of One String Appear in Another

A string is created using the letters of another string. Letters are case sensitive. Write a C++ program to verify that the letters in the second string appear in the first string. Return true otherwise false.

A string is created by using the letters of another string. Letters are case sensitive.

Test Data:
("CPP", "Cpp") -> false
("Java", "Ja") -> true
("Check first string", "sifC") ->true

Sample Solution:

C++ Code:

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

using namespace std; // Using the standard namespace

// Function to check if str1 contains all letters from str2, regardless of case
bool test(string str1, string str2) {
	int ctr = 0; // Counter to track matches between str1 and str2 characters

	// Loop through each character in str2
	for (int i = 0; i < str2.size(); i++) {
		// Loop through each character in str1
		for (int j = 0; j < str1.size(); j++) {
			// If the characters match (case-sensitive), increment the counter and break
			if (str2[i] == str1[j]) {
				ctr++;
				break;
			}
		}
	}

	// Return true if the counter equals the size of str2 and str1 is equal or longer than str2
	return str2.size() == ctr && str1.size() >= str2.size();
}

int main() {
	// Define test strings str1 and str2, then perform tests
	string str1 = "CPP"; // Test string 1
	string str2 = "Cpp"; // Test string 2
	cout << "String1: " << str1; // Display string1
	cout << "\nString2: " << str2; // Display string2
	cout << "\nCheck first string contains letters from the second:\n";
	cout << test(str1, str2) << endl; // Call the test function and display the result

	// Repeat the same process for different strings
	str1 = "Java";
	str2 = "Ja";
	cout << "\nString1: " << str1;
	cout << "\nString2: " << str2;
	cout << "\nCheck first string contains letters from the second:\n";
	cout << test(str1, str2) << endl;

	str1 = "Check first string";
	str2 = "sifC";
	cout << "\nString1: " << str1;
	cout << "\nString2: " << str2;
	cout << "\nCheck first string contains letters from the second:\n";
	cout << test(str1, str2) << endl;
}

Sample Output:

String1: CPP
String2: Cpp
Check first string contains letters from the second:
0

String1: Java
String2: Ja
Check first string contains letters from the second:
1

String1: Check first string
String2: sifC
Check first string contains letters from the second:
1

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to determine if all characters in a second string appear in a first string, considering case sensitivity.
• Write a C++ program that reads two strings and checks if the letters of the second form a subsequence of the first.
• Write a C++ program to verify that each character in one string is contained in another string regardless of order.
• Write a C++ program to compare two strings and return true if every character in the second string exists in the first.

C++ Code Editor:

Click to Open Editor

Contribute your code and comments through Disqus.

Previous C++ Exercise: Reverse the words of three or more lengths in a string.