Help me see what is wrong with the Program (Memory Sharing)

For more information, see what is wrong with the Program (Memory Sharing)-Linux general technology-Linux programming and kernel information. /* Memory1.c */

# Include
# Include
# Include
# Include

# Define SHMKEY 75
Int shmid;

Int main ()
{
Int * pint = 0, m, n, result;
Char * addr1 = 0, operator;
Int judge;


// Printf ("m = % d, operator = % c, n = % d \ n", m, operator, n); // for debugging

Shmid = shmget (SHMKEY, 0777 | IPC_CREAT );
If (-1 = shmid)
{
Printf ("creat shm error ");
Return-1;
}
Addr1 = (char *) shmat (shmid, 0, 0 );
If (-1 = (int) addr1)
{
Printf ("attach shm error! \ N ");
Return-1;
}
Printf ("addr1 0x % x \ n", addr1 );
While (1)
{/* Subinput */
Printf ("Enter the formula for calculation: (such as 12 + 45) \ n"); // note that there is no space in the middle
Scanf ("% d % c % d", & m, & operator, & n );
Pint = (int *) addr1;
* Pint = 0;
Pint ++;
* Pint = m;
Pint ++;
* Pint = (int) operator;
Pint ++;
* Pint = n;
Pint ++;
Pint = (int *) addr1;
* Pint = 256;
While (* pint! = 255 );
Pint ++;
Result = * pint;
Pint --;
* Pint = 0;
Printf ("reslt = % d \ n", result );
Printf ("zookeeper? Too many requests. (0 continue/1 end) \ n ");
Scanf ("% d", & judge );
If (judge = 1)
{
Break;
}
}
Return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~

/* Memory2.c */

# Include
# Include
# Include
# Include

Int shmid;

Int main ()
{
Int * pint, result, m, n;
Char * addr2;
Char operator;

Shmid = shmget (75,1024, 0777 | IPC_CREAT );
If (-1 = shmid)
{
Printf ("creat shm error ");
Return-1;
}
Addr2 = shmat (shmid, 0, 0 );
If (-1 = (int) addr2)
{
Printf ("attach shm error! \ N ");
Return-1;
}

Pint = (int *) addr2;
While (0 = * pint );
Pint ++;
M = * pint;
Pint ++;
Operator = * pint;
Pint ++;
N = * pint;
Switch (operator)
{
Case '+': result = m + n; break;
Case '-': result = m-n; break;
Case '*': result = m * n; break;
Case '/': result = m/n; break;
}
Pint = (int *) addr2;
* Pint = 255;
Pint ++;
* Pint = result;
Return 0;

}
~~~~~~~~~~~~~~~~~~

Run:

# Gcc-o memory1 memory1.c

# Gcc-o memory2 memory22.c

#./Memory1 // window 1

#./Memory2 // window 2

Window 1 appears // when the result ends, select whether to continue as prompted.

#./Memory2 // continue testing

Function to be implemented: file memory1 writes an operation formula to the shared memory segment, and then file memory2 writes the calculation result to the memory again. Then memory1 reads the result from the memory and outputs the result.
Problem: All the results below four digits are correct, but the results with five or more digits are sometimes right and sometimes wrong .. I don't know why. Please help me find out where the problem is...