C / C++ / MFC

class CLASS_I2CIO {
public:
	CLASS_I2CIO();
	CLASS_I2CIO(char Device, int Address);
	CLASS_I2CIO(int width, int length, int height)
		        : m_width(width), m_length(length), m_height(height)
		    {}

	CLASS_I2CIO(char *x1, int y1); // :

this is the one which fails 
	CLASS_I2CIO(char *x1, int y1, int Width, int Height);

private:
    char *device;
    int address;
    int width, height;

public:
	virtual ~CLASS_I2CIO();
	int FileDescriptor = 0;

	// class variables
	__u8 reg;  /* Device register to access */
	__s32 res;
	char buffer[10]= { }; // clear buffer  - was not initialized

CLASS_I2CIO(char Device, int Address);

class C_VNA {
   C_VNA();
   ...
   CLASS_I2CIO   i2c_ads1115_test; // just declaring the type of the member variable here
};
...
// constructors
// initialize the class members here (only needed when not using default constructor)
C_VNA::C_VNA()
 : i2c_ads1115_test(DEVICE_I2C,ADDRESS_ADS) 
{
   // more initialization code
}

Stefan_Lang wrote:

had to remove tags - for some reason they are not working!?

Vaclav_ wrote:

The error "points " to #define which is redefined in this class - temporary for test purposes.

#include "spi.h" // #defines DEVICE_SPI, etc

 #define DEVICE_SPI_"dev/spidev0.0" // Temporary define 

class C_VNA {
    // ...
};

#ifdef DEVICE_SPI
#define ORIG_DEVICE_SPI DEVICE_SPI
#undef DEVICE_SPI
#endif
#define DEVICE_SPI "dev/spidev0.0"
// your code here that uses the temporary DEVICE_SPI

#ifdef ORIG_DEVICE_SPI
#undef DEVICE_SPI
#define DEVICE_SPI ORIG_DEVICE_SPI
#undef  ORIG_DEVICE_SPI
#endif

CLASS_I2CIO   i2c_ads1115(DEVICE_I2C,ADDRESS_ADS);

CLASS_I2CIO   i2c_ads1115_test(const char* DEVICE_I2C, int ADDRESS_ADS);

CPallini wrote:

I would keep it simple: an unsigned cannot be less than zero, full stop.

Member 14088880 wrote:

So implicitly an unsigned int is not capable of an access violation Below / before an array's first element given the pointer arithmetic. All that being said it does not seem at all necessary to test it.

void myfunction(int array[], unsigned int count)
{
    for (unsigned x = 0; x < count; x++)
        ...
}

myfunction(array, -1);

#include <stdio.h>

//void print_iterator(int integer_array[], int index)
void print_iterator(int integer_array[], unsigned int index)
{
	unsigned int i;

	if(index < 0)
	{
		printf("Index violation!\n");
		return;
	}
	else
		printf("Passed index validation: %d, as %u\n", index, index);

	for(i = 0; i < index; i++)
	{
//		printf("%d\t", integer_array[i]);

		if(i == 20)
		{
			printf("Loop overrun, undefined behavior\n");
			return;
		}
	}
}

main()
{
	int ints[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
 
	print_iterator(ints, -1);
}

Quote:

Passed index validation: -1, as 4294967295
Loop overrun, undefined behavior
Press any key to continue . . .

Quote:

Index violation!
Press any key to continue . . .

Member 14088880 wrote:

If the index argument is declared as an unsigned int, it seems it will ALWAYS pass the bounds check when -1 is passed as the parameter...

Member 14088880 wrote:

If it is declared as an int (uncomment the first function line, comment out the second one) it will work properly:

void print_iterator(int integer_array[], size_t integer_array_len, size_t index)

print_iterator(ints, sizeof(ints) / sizeof(int), (size_t) -1);