C strrev() Function

The strrev() function in C is used to reverse a string. It is not a standard function in the C library, but it can be implemented easily. The function reverses the characters in a string in-place.

Syntax of strrev()

The syntax of the strrev() function is as follows:

                        
char *strrev(char *str);
                        
                    

The function takes one argument:

• str: A pointer to the string that will be reversed. The string is reversed in-place, meaning the original string is modified.

The function returns a pointer to the reversed string.

Example of strrev() Function

Here is an example that demonstrates how the strrev() function works. Since strrev() is not a part of the standard C library, we will implement it manually.

                        
#include <stdio.h>>
#include <string.h>>
        
// Function to reverse a string
char* strrev(char* str) {
    int len = strlen(str);
    int i, j;
    char temp;
                
// Reversing the string
    for (i = 0, j = len - 1; i < j; i++, j--) {
        temp = str[i];
            str[i] = str[j];
            str[j] = temp;
    }
    return str;
    }
        
int main() 
{
    char str[] = "Hello, World!";
                
    printf("Original String: %s\n", str);
                
    // Reversing the string
    strrev(str);
                
    printf("Reversed String: %s\n", str);
                
    return 0;
}
                        
                    

Explanation of the Example

In this example:

• The function strrev() is implemented manually to reverse the input string.
• We initialize two variables, i and j, to point to the beginning and end of the string, respectively.
• In a loop, characters at positions i and j are swapped until i is greater than or equal to j.
• The reversed string is then printed.

Important Notes

• The strrev() function is not part of the C standard library, so you need to implement it yourself or use a third-party library that includes it.
• The function reverses the string in-place, which means it modifies the original string. There is no need to allocate additional memory for the reversed string.
• Make sure the string is null-terminated before passing it to the function. Otherwise, it may lead to undefined behavior.