Access violation Internal string variable

Question

Hello ,
I have a code here that is kind of tricky to me. The code works fine when it it in the
main function of my C program. BUT when I try to run the same code in a custom function that I create, I get the error
Access violation writing location 0xNNNNNNNN  (N being any hex number)
So after reading on or two comments on the internet I understood that the variable in the custom might have been allocated memory in some read only area. BUT I need to use it in my custom function. So could anybody explain me what exactly is happenig and how
to move around it ?
Below is the code
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
void test(void);
void main(void)
test();
_getch();
void test(void)
{char const * typeOP;
int repType = 0;
  do
        system("cls");
    printf("Enter a string)\n");
        typeOP = (const char*)malloc(sizeof(const char));
    fflush(stdin);
    if (!scanf_s("%s", typeOP))
            printf("ERROR\n");
            repType = 1;
    } while (repType);
_getch();
Below is the code that works fine
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
void main(void)
char const * typeOP;
int repType = 0;
do
system("cls");
printf("Enter a string)\n");
typeOP = (const char*)malloc(sizeof(const char));
fflush(stdin);
if (!scanf_s("%s", typeOP))
printf("ERROR\n");
repType = 1;
} while (repType);
_getch();

Answer 1

I see three obvious problems with the code:
The first, you seem to see yourself -- you are modifying a char const * string.  This is bad form.  Having said that, I doubt that it would cause a crash, because the actual address returned by malloc will be to memory that is read/write. 
Just get rid of the const though.  You only use const to announce you do not intend to change the data that typeOP points to.  However you obviously do intend to change the data.
The huge issue is that you are using malloc to allocate enough space to hold exactly one char, but you are trying to store an entire array of them in there.  Normally, if you want to malloc the storage, you would use something like:
typeOP = (const char*)malloc(1000 *sizeof(const char));
(You can replace 1000 with the size of the largest possible string you would expect someone to type -- be sure to include 1 for the null terminator).  This will allocate storage for an entire string.  scanf also has format specifiers to prevent
the user from entering more data than you provided storage.
Finally you leak the memory you allocated.   You need a free call before the end of your loop to release the memory.  Again, failure to release the memory won't cause a crash (unless you eventually leak so much that Windows cannot give you
any more)
Lastly, as a style note:  I would suggest using a fixed size array in this scenario instead of malloc -- then you cannot forget to free the memory. 
Something like:
char typeOP[1000]; // also remove the line with malloc