Reversing a string in C

[Sathyaish]

This one question is asked modally in most Microsoft interviews. I started to contemplate various implementations for it. This was what I got.

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


char* StrReverse(char*);
char* StrReverse1(char*);
char* StrReverse2(char*);
void StrReverse3(char*);
void StrReverse4(char*);

int main(void)
{

	char str[50];
	int temp=0;

	printf("Enter a string: ");
	scanf("%s", str);
	printf("The reverse of the string is: %s\n", StrReverse(str));
	printf("The reverse of the string is: %s\n", StrReverse1(str));
	printf("The reverse of the string is: %s\n", StrReverse2(str));

	StrReverse3(str);
	printf("The reverse of the string is: %s\n", str);
	
	//Get back the original string
	StrReverse3(str);
	
	//Reverse it again
	printf("The reverse of the string is: ");
	StrReverse4(str);
	printf("\n");

	scanf("%d", &temp);

}


char* StrReverse(char* str)
{
	char *temp, *ptr;
	int len, i;

	temp=str;
	for(len=0; *temp !='\0';temp++, len++);
	
	ptr=malloc(sizeof(char)*(len+1));
	
	for(i=len-1; i>=0; i--) 
		ptr[len-i-1]=str[i];
	
	ptr[len]='\0';
	return ptr;
}

char* StrReverse1(char* str)
{
	char *temp, *ptr;
	int len, i;

	temp=str;
	for(len=0; *temp !='\0';temp++, len++);
	
	ptr=malloc(sizeof(char)*(len+1));
	
	for(i=len-1; i>=0; i--) 
		*(ptr+len-i-1)=*(str+i);
	
	*(ptr+len)='\0';
	return ptr;
}

char* StrReverse2(char* str)
{
	int i, j, len;
	char temp;
	char *ptr=NULL;
	i=j=len=temp=0;

	len=strlen(str);
	ptr=malloc(sizeof(char)*(len+1));
	ptr=strcpy(ptr,str);
	for (i=0, j=len-1; i<=j; i++, j--)
	{
		temp=ptr[i];
		ptr[i]=ptr[j];
		ptr[j]=temp;
	}
	return ptr;
}

void StrReverse3(char* str)
{
	int i, j, len;
	char temp;
	i=j=len=temp=0;

	len=strlen(str);
	for (i=0, j=len-1; i<=j; i++, j--)
	{
		temp=str[i];
		str[i]=str[j];
		str[j]=temp;
	}
}



/*A coooooooooool way of reversing a string by recursion. I found it at this web address
http://www.geocities.com/cyberkabila/datastructure/datastructuresright_reversestring.htm
*/

void StrReverse4(char *str)
{
	if(*str)
	{
		StrReverse4(str+1);
		putchar(*str);
	}
}

Then, I read one guy saying a string could be reversed in one single sweep with the exclusive OR operator. Since then I've been itching to know how. If someone can please share with me, the code to reverse a string with the XOR operator, I'll be grateful.