C++ Exercises: Check if a given string begins with 'abc' or 'xyz'

Last update on April 07 2025 12:57:51 (UTC/GMT +8 hours)

Starts with 'abc' or 'xyz', Return It or Empty

Write a C++ program to check if a given string begins with 'abc' or 'xyz'. If the string begins with 'abc' or 'xyz' return 'abc' or 'xyz' otherwise return the empty string.

Sample Solution:

C++ Code :

#include <iostream> // Including the input/output stream library
using namespace std; // Using the standard namespace

// Function that checks the starting substring of the input string
string test(string s1) 
{
    // Check if the first three characters of s1 are "abc"
    if (s1.substr(0, 3) == "abc")
    {
        return "abc"; // Return "abc" if the first three characters match "abc"
    }
    // Check if the first three characters of s1 are "xyz"
    else if (s1.substr(0, 3) == "xyz")
    {
        return "xyz"; // Return "xyz" if the first three characters match "xyz"
    }
    else
    {
        return ""; // Return an empty string if neither "abc" nor "xyz" is found at the beginning
    }
}

// Main function
int main() 
{
    // Output the results of test function with different input strings
    cout << test("abc") << endl;     // Output for "abc"
    cout << test("abcdef") << endl;  // Output for "abcdef"
    cout << test("C") << endl;       // Output for "C"
    cout << test("xyz") << endl;     // Output for "xyz"
    cout << test("xyzsder") << endl; // Output for "xyzsder"
    return 0;    // Return statement indicating successful termination of the program
}

Sample Output:

abc
abc

xyz
xyz

Visual Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program that checks whether an input string begins with "abc" or "xyz" and returns that substring; if not, return an empty string.
• Write a C++ program to verify the prefix of a string for "abc" or "xyz" and output the matching prefix or nothing if no match is found.
• Write a C++ program that reads a string and prints "abc" if it starts with "abc", "xyz" if it starts with "xyz", otherwise prints an empty string.
• Write a C++ program to examine an input string's beginning and return the substring "abc" or "xyz" when detected, returning a blank string if neither is present.

C++ Code Editor:

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