C strstr() Function

Posted in C Tutorial

Updated on Jan 14, 2024

By Mari Selvan

👁️ 277 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the C programming language, working with strings is a common and essential task.

The strstr() function is part of the C Standard Library (<string.h>) and is used for string searching.

It locates the first occurrence of a substring within another string and returns a pointer to the beginning of the found substring.

In this tutorial, we'll explore the usage and functionality of the strstr() function in C.

💡 Syntax

The syntax for the strstr() function is as follows:

Syntax

Copied

char *strstr(const char *haystack, const char *needle);

haystack: The string to be searched.
needle: The substring to search for within the haystack.

📄 Example

Let's dive into an example to illustrate how the strstr() function works.

strstr.c

Copied

#include <stdio.h>
#include <string.h>

int main() {
  const char * haystack = "This is a simple example.";
  const char * needle = "simple";

  // Search for the substring
  char * result = strstr(haystack, needle);

  // Output the result
  if (result != NULL) {
    printf("Substring found: %s\n", result);
  } else {
    printf("Substring not found.\n");
  }

  return 0;
}

💻 Output

Output

Substring found: simple example.

🧠 How the Program Works

In this example, the strstr() function is used to search for the substring "simple" within the string "This is a simple example."

↩️ Return Value

The strstr() function returns a pointer to the first occurrence of the needle in the haystack. If the needle is not found, it returns NULL.

📚 Common Use Cases

The strstr() function is particularly useful when you need to determine if a specific substring exists within a larger string and locate its position. It's commonly employed in scenarios where you want to extract or manipulate portions of text.

📝 Notes

The strstr() function is case-sensitive, meaning that it distinguishes between uppercase and lowercase letters.
If you need a case-insensitive search, you can use other functions or manually convert the strings to lowercase (or uppercase) before calling strstr().

🎢 Optimization

The strstr() function is optimized for efficiency. However, for large strings and frequent searches, consider storing the result in a variable if you need to use it multiple times to avoid redundant computations.

🎉 Conclusion

The strstr() function in C is a powerful tool for searching for substrings within strings. It provides flexibility in dealing with different types of data and enables conditional logic based on the result.

Feel free to experiment with different strings and substrings to deepen your understanding of the strstr() function. Happy coding!