Enclave field not working, but there is no error - visual-studio

Question

I'm trying make simple code call an enclave field and just add 1.
I'm reference this site : https://software.intel.com/en-us/articles/getting-started-with-sgx-sdk-f...
After it finishes, there is no error, but the enclave code is not working.
Here is my project.zip code with Visual Studio 2017 https://drive.google.com/open?id=13trTAamhNWaz2Q2BRDtUFP5qCX8Syyuc
app.cpp
#include <stdio.h>
#include <Windows.h>
#include <tchar.h>
#include "sgx_urts.h"
#include "Enclave1_u.h"
#define ENCLAVE_FILE _T("Enclave1.signed.dll")
int main() {
int a = 1;
int i = 0;
sgx_enclave_id_t eid;
sgx_status_t ret = SGX_SUCCESS;
sgx_launch_token_t token = { 0 };
int updated = 0;
ret = sgx_create_enclave(ENCLAVE_FILE, SGX_DEBUG_FLAG, &token, &updated, &eid, NULL);
if (ret != SGX_SUCCESS)
{
printf("APP error%#x, failed to create enclave. \n", ret);
return -1;
}
int *ptr = &a;
printf("%d\n",*ptr);
while (i<5) {
foo(eid, ptr);
printf("%d\n", *ptr);
Sleep(1000);
i++;
}
if (SGX_SUCCESS != sgx_destroy_enclave(eid))
return -1;
}
Enclave1.edl
enclave {
from "sgx_tstdc.edl" import *;
trusted {
/* define ECALLs here. */
public void foo([in, size = 4]int *ptr);
};
untrusted {
/* define OCALLs here. */
};
};
Enclave1.cpp
#include "Enclave1_t.h"
#include "sgx_trts.h"
#include <string.h>
void foo(int *ptr)
{
if (*ptr == 1) *ptr == 43971;
*ptr += 1;
}
I expected it to print:
43971, 43972, 43973, 43974 .....
But the result is:
1, 1, 1, .........
What did I miss?

Answer 1

i solved this problem.
foo needs [out] instad of [in] so Enclave1.edl should
enclave { from "sgx_tstdc.edl" import *;
trusted {
/* define ECALLs here. */
public void foo([out, size = 4]int *ptr);
};
untrusted {
/* define OCALLs here. */
};
};
project1.signed.dll file is not updated on debug folder. so i try rebuild project and it updated. I'm realized this file is enclave field itself
IF state grammar is wrong. it should be if (*ptr == 1) *ptr = 43971;