C program to reverse a string !!

Below is the complete working example for string reverse fuction in C programming language.

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

//strrev function using arrays
void str_rev_arry(char *str)
{
    int len = strlen(str);
    int i=0,j=len-1;
    for(i=0;i<len/2;i++,j--)
    {
        char temp = str[i];
        str[i] = str[j];
        str[j] = temp;
    }
}

//strrev function using pointers
void str_rev_ptr(char *str)
{
    int len = strlen(str);
    int i;
    char *begin, *end;
    begin = str;
    end = str+len-1;
    for(i=0;i<len/2;i++)
    {
        char temp = *begin;
        *begin = *end;;
        *end = temp;
        begin++;
        end--;
    }
}

//strrev function using recursion
void str_rev_rec(char *str, int begin, int end)
{
    char temp;
    if(begin>=end)
        return;
    temp = *(str+begin);
    *(str+begin) = *(str+end);
    *(str+end) = temp;
    str_rev_rec(str, ++begin, --end);
}
main()
{
    char str[]="Hello string";
    int len,begin,end,choice;
    printf("Enter the String which is to be reversed\n");
    printf("1. Using Arrays\n2. Using Pointers\n3. Using Recursion\n4. Exit\n");
    printf("Enter the method choice\n");
    scanf("%d",&choice);
    switch(choice)
    {
        case 1:
                printf("before reverse the string is '%s'\n",str);
                str_rev_arry(str);
                printf("after reverse the string is '%s'\n",str);
                break;
        case 2:
                printf("before reverse the string is '%s'\n",str);
                str_rev_ptr(str);
                printf("after reverse the string is '%s'\n",str);
                break;
        case 3:
                len = strlen(str);
                begin = 0;
                end = len-1;
                printf("before reverse the string is '%s'\n",str);
                str_rev_rec(str,begin,end);
                printf("after reverse the string is '%s'\n",str);
                break;
        default:
                printf("wrong choice\n");
                break;
    }
}