select

Returns ifTrue when condition is encrypted true, ifFalse otherwise. Since encrypted values cannot be branched on with if, select is the only way to implement conditional logic on encrypted data. No computation is performed on the values themselves, it is purely a selection.

Supported types: euint16, euint256, eint16, eint256

TIP

select is the encrypted equivalent of a ternary operator (condition ? a : b). Since encrypted values cannot be branched on with if, use select for all conditional logic.

Usage

// Confidential max(a, b)
ebool aIsGreater = Nox.gt(a, b);
euint256 maxValue = Nox.select(aIsGreater, a, b);
Nox.allowThis(maxValue);

// Apply a fee only if balance exceeds threshold
ebool exceedsThreshold = Nox.gt(balance, threshold);
euint256 fee = Nox.select(exceedsThreshold, feeAmount, zeroAmount);
euint256 finalBalance = Nox.sub(balance, fee);
Nox.allowThis(fee);
Nox.allowThis(finalBalance);

Signature

function select(ebool condition, euint256 ifTrue, euint256 ifFalse) internal returns (euint256)

Example	Result	Reason
Select(true, 42, 100)	42	Condition is true
Select(false, 42, 100)	100	Condition is false