Substring Search Patterns in DSA C - Build from Scratch

Substring Search Patterns

📖 Scenario: You are building a simple text search tool. It helps find if a small word or pattern exists inside a bigger text.Imagine you have a book and want to find if a certain word appears in it.

🎯 Goal: Build a program that checks if a given pattern is inside a text using substring search.You will create the text and pattern, then write code to find if the pattern exists in the text.

📋 What You'll Learn

Create a string variable called text with the value "hello world"

Create a string variable called pattern with the value "world"

Write a function called contains_pattern that takes text and pattern and returns 1 if pattern is found in text, else 0

Use a simple loop and comparison to check for the pattern inside the text

Print "Pattern found" if the pattern exists in the text, else print "Pattern not found"

💡 Why This Matters

🌍 Real World

Substring search is used in text editors, search engines, and data filtering tools to find words or patterns inside larger texts.

💼 Career

Understanding substring search helps in software development roles involving text processing, search features, and data analysis.

1

Create the text and pattern strings

Create a string variable called text and set it to "hello world". Also create a string variable called pattern and set it to "world".

DSA C

# Your code here to create text and pattern strings

Hint

Use char text[] = "hello world"; and char pattern[] = "world"; to create the strings.

2

Write the contains_pattern function header

Write a function called contains_pattern that takes two parameters: char *text and char *pattern. The function should return an int.

DSA C

#include 

char text[] = "hello world";
char pattern[] = "world";

// Write function header for contains_pattern
int contains_pattern(char *text, char *pattern) {
    // Your code here
}

Hint

Write int contains_pattern(char *text, char *pattern) to start the function.

3

Implement the substring search logic

Inside the contains_pattern function, write code to check if pattern exists inside text. Return 1 if found, else return 0. Use loops and character comparisons.

DSA C

#include 

char text[] = "hello world";
char pattern[] = "world";

int contains_pattern(char *text, char *pattern) {
    // Use loops to check if pattern is in text
    // Your code here
}

Hint

Use nested loops to compare each character of pattern with text starting at each position.

4

Print the search result

Call contains_pattern(text, pattern) in main. If it returns 1, print "Pattern found". Otherwise, print "Pattern not found".

DSA C

#include 

char text[] = "hello world";
char pattern[] = "world";

int contains_pattern(char *text, char *pattern) {
    int i, j;
    for (i = 0; text[i] != '\0'; i++) {
        for (j = 0; pattern[j] != '\0'; j++) {
            if (text[i + j] != pattern[j]) {
                break;
            }
        }
        if (pattern[j] == '\0') {
            return 1;
        }
    }
    return 0;
}

int main() {
    // Your code here
}

Hint

Use if (contains_pattern(text, pattern)) and print accordingly.