Why using `!=X` instead of `> X` is cheaper in solidity

Comparison operator requires the EVM to perform a subtraction between the two values

  • When a comparison operator is used on uint256 values, it requires the EVM to perform a subtraction operation between the two values, which takes up more gas than a simple check for equality.

  • When we use !=X for comparison, the EVM checks if the value is non-zero by simply checking the zero flag, which is more efficient in terms of gas cost compared to checking for a positive value using > X. This is because checking for a positive value requires the EVM to perform a subtraction operation to determine whether the value is positive or not.

  • Therefore, in Solidity, it is more gas-efficient to use !=X instead of > X when comparing unsigned integer values.