Thread: jbyteArray to LPBYTE conversion

I'm a beginner in Windows Programming or I'll say I don't know much at all.
In my program, I'm using JNI to import a DLL file written in Windows API into my Java program.

In the C program that direct the JNI variables into DLL Functions, I'm required to convert jbyte* which is similar to byte * to LPBYTE as the function parameters are of LPBYTE type.

I've tried the code below as a separate running program and it works.

Code:

	byte t2 ='4';
	printf( "number value :  %c\n", t2 );
	printf( "number address : %p\n", &t2 );
	
	LPBYTE test = new byte[256];
	test = &t2;
	printf("test address : %p\n",test);
	printf("test value : %c\n\n",*test);

However, when I port it into my real program using this code:

Code:

	jbyte *lpbMRZ_local = (*env)->GetByteArrayElements(env, lpbMRZ, 0);
	jsize len = (*env)->GetArrayLength(env, lpbMRZ);
        int i=0, j = 0;
	DWORD slen=len;
	printf("Length = %d %lu\n",len, slen);

	for( i=0; i<len; i++)
		printf("%lu ",lpbMRZ_local[i]);
	printf("\n");

	LPBYTE lpbMRZ_lp = &lpbMRZ_local;

I get this error, referring to

Code:

C:\eclipse\workspace\ePPTestApp\src>cl -IC:\j2sdk1.4.2_12\include -IC:\j2sdk1.4.2_12\include\win32      -LD JavaBACInterface.c -Febacinterface.dll
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 13.10.3077 for 80x86
Copyright (C) Microsoft Corporation 1984-2002. All rights reserved.

JavaBACInterface.c
JavaBACInterface.c(46) : error C2275: 'LPBYTE' : illegal use of this type as an expression
c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinDef.h(150) : see declaration of 'LPBYTE'
JavaBACInterface.c(46) : error C2146: syntax error : missing ';' before identifier 'lpbMRZ_lp'
JavaBACInterface.c(46) : error C2144: syntax error : '<Unknown>' should be preceded by '<Unknown>'
JavaBACInterface.c(46) : error C2144: syntax error : '<Unknown>' should be preceded by '<Unknown>'
JavaBACInterface.c(46) : error C2143: syntax error : missing ';' before 'identifier'
JavaBACInterface.c(46) : error C2065: 'lpbMRZ_lp' : undeclared identifier
JavaBACInterface.c(46) : warning C4047: '=' : 'int' differs in levels of indirection from 'jbyte ** '

I've been trying of all sort of ways to perform the conversion from byte* to LPBYTE for the week. And this is my last resort. I don't even know what's wrong.

So, may I know how to convert common byte* into LPBYTE?

P/S: I post the question here as it involves LPBYTE, windows api data type. Please inform me if I should post elsewhere.

I've actually tried that. I thought my pointer referencing was invalid so I tried the code below earlier. I wonder if anybody has done JNI to import a ready-built DLL library.

Code:

LPBYTE lpbMRZ_lp = lpbMRZ_local;

I solved it by copying the content one by one. I should have thought about this earlier.

Code:

LPBYTE convert2LPBYTE(unsigned char * input,int input_size){
	DWORD size = (DWORD)input_size;
	printf("size input: %lu\n",size);
	LPBYTE output = (LPBYTE)malloc(size*sizeof(input[0]));
	for(DWORD i = 0 ; i <size; i++){
		output[i] = input[i];
		printf("%c",output[i]);
	}
	printf("\n");
	return output;
}

Anyway, I failed to retrieve the real sizeof(input) as it's always only fixed at 4. So, I have another parameter to fix the size of each array to be converted.

Any better idea?

The array in the parameter has fixed size instead of being dynamically allocated. So, its size should be retrievable by using sizeof ?
What else can i do?