reverse_string.c

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

/* String.h includes one variable type, one macro, and several functions for 
manipulating arrays of characters.*/

void reverseWithRecursion(char*, int , int); //Function definitions

/*void reverseFunction(char *string)
{
	strrev(string);
}*/

char *reverseWithoutFunction(char *string)
{
	char *reverse;
	int n, c, d;

	n = strlen(string);
	reverse = (char*)malloc(n * 1);

	for (c = n - 1, d = 0; c >= 0; c--, d++){
		reverse[d] = string[c];
	}

	reverse[d] =  '\0';
	return (char *)reverse;
}

int stringLength(char *pointer)
{
	int c = 0;

	while( *(pointer + c) != '\0')
	{
		c++;
	}

	return c;
}

void reverseWithPointer(char *string)
{
	int length, c;
	char *begin, *end, temp;

	length = stringLength(string);
	begin = string;
	end = string;

	for (c = 0; c < length - 1; c++)
	{
		end ++;
	}

	for (c = 0; c < length/2; c++)
	{
		temp = *end;
		*end = *begin;
		*begin = temp;

		begin ++;
		end --;
	}
}

void reverseWithRecursion(char *x, int begin, int end)
{
	char c;

	if(begin>= end)
	{
		return;
	}

	c = *(x+begin);
	*(x+begin) = *(x+end);
	*(x+end) = c;

	reverseWithRecursion(x, ++begin, --end);
}

int main()
{
	char arr[100];
	char *rev;

	printf("Enter a string to reverse\n");
	gets(arr); //reads string in from stdin and stores into string pointed to by arr.

	//rev = reverseWithoutFunction(arr);
	//reverseWithPointer(arr);
	reverseWithRecursion(arr, 0, strlen(arr)-1);

	printf("Reverse of entered string is \n%s\n", arr);

	return 0;
}