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strrev() Function in C

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Prerita Agarwal
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23 Jul, 2024 @ 01:30 PM


In the C language, renowned for its extensive library of built-in functions, string handling functions play a vital role in manipulating text data. Among these, the strrev() function stands out. This function reverses a string, offering versatility in tasks such as checking palindromes and modifying file paths.

strrev() function in C

Let's explore the strrev() function, its usage, and its role in C programming.

Understanding the strrev() Function

The strrev() function is a built-in function in C contained in the string.h library. As its name suggests, strrev() is used to reverse the order of characters in a string.


#include <string.h>

char* strrev(char* str);

In the above syntax, the strrev() function takes a single argument: the string str that you want to reverse. It returns the reversed string.

It's crucial to note that the strrev() function modifies the original string—it doesn't create a new string with reversed characters


str parameter represents the string that the function will reverse. It is a pointer to the character array or string that you want to reverse. The function modifies this string in place, reversing its contents.

Return Value

The strrev() function does not return any value. It operates directly on the string provided as input, reversing its content in place. Therefore, there is no explicit return value.

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An Example of strrev() Function in C

Here's a simple example to illustrate how the strrev() function works:

  • C


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

int main() {
   char str[100] = "Hello, World!";
   printf("Before strrev: %s\n", str);
   printf("After strrev: %s\n", str);
   return 0;

In the above program, strrev() reverses the string stored in str. Before calling strrev(), str contains "Hello, World!". After calling strrev(), str contains "!dlroW ,olleH", which is the reverse of the original string.


!dlroW ,olleH

Also read - Bit stuffing program in c

Exceptions of the Function strrev in C

There are exceptions of the strrev() function in C:

  • Portability: strrev() may not be available in all C compilers or platforms. Code using strrev() may not compile or behave consistently across different systems.
  • Non-Standard Function: strrev() is not part of the ANSI C standard, which means its behavior and implementation can vary across different environments.
  • Limited Support for Special Characters: strrev() may not handle special characters or multibyte characters correctly, leading to unexpected behavior or data corruption in certain cases.

Drawbacks strrev() Function in C

There are few drawbacks strrev() function in C:

  • In-Place Modification: strrev() operates directly on the original string provided as input, modifying it in place. This can be problematic if the original string needs to be preserved for further processing.
  • Lack of Bounds Checking: strrev() does not perform bounds checking on the input string. If the input string is not properly null-terminated or if memory allocation for the string is insufficient, it can lead to buffer overflows and undefined behavior.
  • Potential for Data Corruption: Since strrev() modifies the original string, it can lead to unintended changes in other parts of the program that rely on the original string's content.
  • Not Thread-Safe: strrev() is not thread-safe, meaning it may cause unexpected behavior in multithreaded environments where concurrent access to the string occurs.
  • Limited Error Handling: strrev() does not provide robust error handling mechanisms. If an error occurs during string reversal, there may not be clear indications of the problem, making debugging challenging.

Key Considerations when Using strrev()

When using strrev(), keep the following points in mind:

  • Library: strrev() is part of the string.h library. You need to include this library to use strrev().
  • Argument: strrev() takes a single argument, a string. It reverses this string in-place.
  • Return value: strrev() returns a pointer to the reversed string.
  • In-place modification: strrev() reverses the string in-place—it does not create a new string. This means that the original string is modified.

Also see, Floyd's Triangle in C

Frequently Asked Questions

What is the strlen function in C?

The strlen function in C returns the length of a string, excluding the null terminator.

What is the strrev algorithm?

The strrev algorithm reverses a string in place by swapping characters from the beginning and end until the middle is reached.

Is strrev() available in all C compilers?

No, strrev() is not part of the ANSI C standard and may not be available in all C compilers, especially on non-Windows platforms.

Does strrev() create a new string?

No, strrev() reverses the string in-place. The original string is modified.

Can strrev() handle strings of any length?

Yes, strrev() can handle strings of any length, provided the string fits in memory.


In C programming, understanding string manipulation is crucial, and the strrev() function serves as a fundamental tool in this process. While it's a simple function that reverses a string, the applications are extensive. However, one must be aware that it directly modifies the original string and that it might not be available in all C compilers. With these considerations in mind, you can use strrev() effectively in your C programming journey. 

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Topics covered
Understanding the strrev() Function
Return Value
An Example of strrev() Function in C
Exceptions of the Function strrev in C
Drawbacks strrev() Function in C
Key Considerations when Using strrev()
Frequently Asked Questions
What is the strlen function in C?
What is the strrev algorithm?
Is strrev() available in all C compilers?
Does strrev() create a new string?
Can strrev() handle strings of any length?