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Explicit Conversions.md

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69 - Explicit Conversions

If the compiler does not allow implicit conversion but you are confident a conversion will work, an explicit type conversion is sometimes possible. This may result in unexpected behaviour and allows you to bypass some security features of the compiler e.g. int to uint

  1. If an integer is explicitly converted to a smaller type, higher-order bits are cut off

  2. If an integer is explicitly converted to a larger type, it is padded on the left (i.e., at the higher order end)

  3. Fixed-size bytes types while explicitly converting to a smaller type and will cut off the bytes to the right

  4. Fixed-size bytes types while explicitly converting to a larger type and will pad bytes to the right.

Slide Screenshot

069.jpg

Slide Deck

  • Type Conversion Developer Applied
  • Unexpected Behavior
  • Bypass Type Security
  • Smaller Type -> Higher Order Cut-off
  • Larger Type -> Higher Order Padded
  • Fixed-size: Bytes bytes1..bytes32
  • Smaller type -> Lower Order Cut-off
  • Larger Type -> Lower Order Padded

References