Someone can explain this?

Question

I really dont understand this.Maybe someone can explain me . I wanted find out how many elements is in dataInput. I'm programming in C

void Calibrate_data(float* dataInput)
{   
    int dataSize = sizeof(*dataInput)/sizeof(float);
    printf("%i and %i",sizeof(*dataInput)/sizeof(float),dataSize);
}

The output is:

1 and 10

Answer 1

This is the wrong format specifier here:

printf("%i and %i",sizeof(*dataInput)/sizeof(float),dataSize);
        ^^

sizeof returns size_t type which is unsigned the correct format specifier is %zu or %Iu in Visual Studio.

Using the wrong format specifier invokes undefined behavior but that does not seem to explain the output of 10 for dataSize which does not make sense since sizeof(*dataInput) will be the size of a float. So we would expect sizeof(*dataInput)/sizeof(float) to be 1, as Macattack said an SSCCE should help resolve that output.