Thread: Using malloc

Having only recently heard of the "malloc" function, supposedly to dynamically change the size of an array, I wanted to adjust my "LoadFile" function to using it, if it does what I think it does. I don't know how to set up the function parameters mainly. Here's the related code I have:

Code:

// the global variable declarations (array sizes given is what should be allocated)

...
unsigned char PrelakeHills04Data[700416]; // The prelake hills layer 4 background
unsigned char *PrelakeHills04MainDataPointer; // malloc requires a pointer to the data
unsigned long PrelakeHills04MemoryUsage;
LPVOID PrelakeHills04DataPointer; // data pointer for use in AlphaBlend and DrawDibDraw functions
BITMAPINFO PrelakeHills04MainInfo;
BITMAPINFOHEADER PrelakeHills04Info;
LPBITMAPINFOHEADER PrelakeHills04InfoPointer;
HBITMAP PrelakeHills04BMPHandle;
struct SceneryData PrelakeHills04;
unsigned char PrelakeHills03Data[343040]; // The prelake hills layer 3 background
unsigned char *PrelakeHills03MainDataPointer;
unsigned long PrelakeHills03MemoryUsage;
LPVOID PrelakeHills03DataPointer;
BITMAPINFO PrelakeHills03MainInfo;
BITMAPINFOHEADER PrelakeHills03Info;
LPBITMAPINFOHEADER PrelakeHills03InfoPointer;
HBITMAP PrelakeHills03BMPHandle;
struct SceneryData PrelakeHills03;
unsigned char PrelakeHills02Data[106496]; // The prelake hills layer 2 background
unsigned char *PrelakeHills02MainDataPointer;
unsigned long PrelakeHills02MemoryUsage;
...

// the function's header (yes, lots of parameters)

char LoadFile(const char FileName[64], char FileType, BITMAPINFOHEADER *BMPInfo, unsigned char *BMPData, char FogUsed, double ObjectScaling, char LoadType, unsigned char *BMPDataPointer, unsigned long *BMPMemoryUsage)
{
	// local variables, setting directories, and setting the file handle (no problems here)
	...

			// filling the structure works fine
			fseek(FileHandle, 14, SEEK_SET); // skip the basic file header data but read from the info header
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 0E through 11
			BMPInfo->biSize = (DWORD)ValuesBase[0]+(DWORD)ValuesBase[1]*256+(DWORD)ValuesBase[2]*65536+(DWORD)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 12 through 15
			BMPInfo->biWidth = (long)ValuesBase[0]+(long)ValuesBase[1]*256+(long)ValuesBase[2]*65536+(long)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 16 through 19
			BMPInfo->biHeight = (long)ValuesBase[0]+(long)ValuesBase[1]*256+(long)ValuesBase[2]*65536+(long)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 2, FileHandle); // bytes 1A and 1B
			BMPInfo->biPlanes = (WORD)ValuesBase[0]+(WORD)ValuesBase[1]*256;
			fread(&ValuesBase, 1, 2, FileHandle); // bytes 1C and 1D
			BMPInfo->biBitCount = (WORD)ValuesBase[0]+(WORD)ValuesBase[1]*256;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 1E through 21
			BMPInfo->biCompression = (DWORD)ValuesBase[0]+(DWORD)ValuesBase[1]*256+(DWORD)ValuesBase[2]*65536+(DWORD)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 22 through 25
			BMPInfo->biSizeImage = (DWORD)ValuesBase[0]+(DWORD)ValuesBase[1]*256+(DWORD)ValuesBase[2]*65536+(DWORD)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 26 through 29
			BMPInfo->biXPelsPerMeter = (long)ValuesBase[0]+(long)ValuesBase[1]*256+(long)ValuesBase[2]*65536+(long)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 2A through 2D
			BMPInfo->biYPelsPerMeter = (long)ValuesBase[0]+(long)ValuesBase[1]*256+(long)ValuesBase[2]*65536+(long)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 2E through 31
			BMPInfo->biClrUsed = (DWORD)ValuesBase[0]+(DWORD)ValuesBase[1]*256+(DWORD)ValuesBase[2]*65536+(DWORD)ValuesBase[3]*16777216;
			fread(&ValuesBase, 1, 4, FileHandle); // bytes 32 through 35
			BMPInfo->biClrImportant = (DWORD)ValuesBase[0]+(DWORD)ValuesBase[1]*256+(DWORD)ValuesBase[2]*65536+(DWORD)ValuesBase[3]*16777216;
			
			BMPMemoryUsage = BMPInfo->biWidth*BMPInfo->biHeight*3; // determine the amount of memory usage - 24-bit BMP's use 3 bytes per pixel
			BMPDataPointer = malloc(BMPMemoryUsage); // allocate the memory for the amount given in the previous statement
			fread(BMPData, 1, BMPMemoryUsage, FileHandle); // read the main image data // reads in BGR format
			...
			
	// rest of function, which works without problems
}

...
// at end of main function
	free(PrelakeHills04MainDataPointer); // release the memory, to avoid memory leaks

What I want to do is call the function like this:

Code:

LoadFile("PrelakeHills04.tga", 2, &PrelakeHills04Info, PrelakeHills04Data, 1, PrelakeHills04.Scaling, 0, PrelakeHills04MainDataPointer, PrelakeHills04MemoryUsage);

I don't know how to set up the function so that it reads the amount of data allocated in the main data array, no more, no less.