Integers

Tact supports a number of primitive data types that are tailored for smart contract use.

Int is the primary number type. Math in smart contracts is always done with integers and never with floating points since floats are unpredictable.

The runtime type Int is always 257-bit signed, so all runtime calculations are done at 257-bit. This should be large enough for pretty much anything you need as it's large enough to hold the number of atoms in the universe.

Persistent state variables can be initialized inline or inside init(). If you forget to initialize a state variable, the code will not compile.

State costs

When encoding Int to persistent state, we will usually use smaller representations than 257-bit to reduce storage cost. The persistent state size is specified in every declaration of a state variable after the as keyword.

Storing 1000 257-bit integers in state costs about 0.184 TON per year.
Storing 1000 32-bit integers only costs 0.023 TON per year by comparison.

All Examples

import "@stdlib/deploy";

contract Strings with Deployable {
 
    // contract persistent state variables
    s1: String = "hello world";
    s2: String = "yes unicode 😀 😅 你好 no escaping"; /// TODO: https://github.com/tact-lang/tact/issues/25 \n \t";
    s3: String;
    s4: String;
    s5: String;
    s6: String;

    init() {
        let i1: Int = -12345;
        let i2: Int = 6780000000; // coins = ton("6.78")

        self.s3 = i1.toString();
        self.s4 = i1.toFloatString(3);
        self.s5 = i2.toCoinsString();

        // gas efficient helper to concatenate strings in run-time
        let sb: StringBuilder = beginString();
        sb.append(self.s1);
        sb.append(", your balance is: ");
        sb.append(self.s5);
        self.s6 = sb.toString();
    }

    receive("show all") {
        dump(self.s1);
        dump(self.s2);
        dump(self.s3);
        dump(self.s4);
        dump(self.s5);
        dump(self.s6);
    }

    receive("show ops") {
        let s: String = "how are you?"; // temporary variable
        dump(s);

        /// TODO: https://github.com/tact-lang/tact/issues/24
        /// dump(self.s1 == "hello world");
        /// dump(self.s1 != s);
    }

    get fun result(): String {
        return self.s1;
    }
}