#include <stdio.h>

void swap(char *str, int i, int j)
{
	char temp = str[i];
	str[i] = str[j];
	str[j] = temp;
}

void rotate(char *str, int n)
{
	int i;
	for(i=0; i<n/2; i++)
	{
		swap(str, i, n-1-i);
	}
}

int main(int argc, char** argv)
{	

	char str[1000];
	printf("Enter a string: ");
	scanf("%[^\n]s", str); 
	/*[^\n] tells scanf() function that receives a 
	string until a new line occurs. */
	int i = 0;
	while(str[i] != '\0')
	{
		i++;
	}
	printf("Original string = %s\n", str);
	rotate(str, i);
	printf("Reversed string = %s\n", str);
	return 0;
}

Enter a string: Surajit Nandy
Original string = Surajit Nandy
Reversed string = ydnaN tijaruS