Count Words with Given Prefix in DSA C++ - Build from Scratch

Count Words with Given Prefix

📖 Scenario: You are building a simple program to help a bookstore find how many book titles start with a certain prefix. This helps the store quickly count books by categories or themes.

🎯 Goal: Create a program that counts how many words in a list start with a given prefix.

📋 What You'll Learn

Create a vector of strings called words with the exact values: "apple", "app", "application", "banana", "band"

Create a string variable called prefix and set it to "app"

Use a for loop with variable word to iterate over words

Inside the loop, use word.compare(0, prefix.size(), prefix) == 0 to check if word starts with prefix

Create an integer variable count to count how many words start with prefix

Print the value of count at the end

💡 Why This Matters

🌍 Real World

Counting words with a specific prefix is useful in search engines, autocomplete features, and organizing data by categories.

💼 Career

This skill helps in software development roles involving text processing, search optimization, and building user-friendly interfaces.

1

Create the list of words

Create a vector of strings called words with these exact entries: "apple", "app", "application", "banana", "band"

DSA C++

#include 
#include 
#include 

int main() {
    // Create vector words with "apple", "app", "application", "banana", "band"
    // Your code here
}

Hint

Use std::vector<std::string> and initialize it with the given words inside curly braces.

2

Set the prefix to search

Create a string variable called prefix and set it to "app"

DSA C++

#include 
#include 
#include 

int main() {
    std::vector words = {"apple", "app", "application", "banana", "band"};
    // Create string prefix and set it to "app"
    // Your code here
}

Hint

Use std::string prefix = "app"; to create the prefix variable.

3

Count words starting with the prefix

Create an integer variable called count and set it to 0. Use a for loop with variable word to iterate over words. Inside the loop, use word.compare(0, prefix.size(), prefix) == 0 to check if word starts with prefix. If yes, increase count by 1.

DSA C++

#include 
#include 
#include 

int main() {
    std::vector words = {"apple", "app", "application", "banana", "band"};
    std::string prefix = "app";
    // Create int count = 0
    // Use for loop: for (const std::string& word : words)
    // Inside loop, check if word starts with prefix using word.compare(0, prefix.size(), prefix) == 0
    // If yes, increment count
    // Your code here
}

Hint

Use a range-based for loop and the compare method of std::string to check the prefix.

4

Print the count result

Print the value of count using std::cout

DSA C++

#include 
#include 
#include 

int main() {
    std::vector words = {"apple", "app", "application", "banana", "band"};
    std::string prefix = "app";
    int count = 0;
    for (const std::string& word : words) {
        if (word.compare(0, prefix.size(), prefix) == 0) {
            count++;
        }
    }
    // Print count
    // Your code here
}

Hint

Use std::cout << count << std::endl; to print the count.