V6011. The expression contains a suspicious mix of integer and real types


The analyzer detected a possible error in an expression where integer and real data types are used together. Real data types include types 'float' and 'double'.

Let's how the error can reveal itself in practice.

boolean IsInRange(int object_layer_width, int object_layer_height)
{
  return  object_layer_height != 0 &&
          object_layer_width/object_layer_height > 0.1 &&
          object_layer_width/object_layer_height < 10;
}

An integer value is compared to the constant '0.1', and that's very strange. Assume the variables have the following values:

  • object_layer_width = 20;
  • object_layer_height = 100;

The programmer expects that division of these numbers will give '0.2'; it fits into the range (0.1..10).

But in fact the division result will be 0. Division is performed over integer data types, and though the result is extended to the type 'double' when compared to '0.1' a bit later, it is too late. To fix the code we need to perform an explicit type conversion beforehand:

boolean IsInRange(int object_layer_width, int object_layer_height)
{
  return  object_layer_height != 0 &&
          (double)object_layer_width/object_layer_height > 0.1 &&
          (double)object_layer_width/object_layer_height < 10;
}

Bugs Found

Checked Projects
336
Collected Errors
12 745