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Calculator

View this sample's code on GitHub

Overview​

This example demonstrates a basic calculator dapp. It uses an orthogonally persistent cell variable to store an arbitrary precision integer that represents the result of the most recent calculation.

The dapp provides an interface that exposes the following methods:

  • add: accepts input and performs addition.
  • sub: accepts input and performs subtraction.
  • mul: accepts input and performs multiplication.
  • div: accepts input, performs division, and returns an optional type to guard against division by zero.
  • clearall: clears the cell variable by setting its value to zero.

This is a Motoko example that does not currently have a Rust variant.

Prerequisites​

This example requires an installation of:

  • Install the IC SDK.
  • Clone the example dapp project: git clone https://github.com/dfinity/examples

Begin by opening a terminal window.

Step 1: Navigate into the folder containing the project's files and start a local instance of the replica with the command:​

cd examples/motoko/calc
dfx start --background

Step 2: Deploy the canister with the command:​

dfx deploy

Step 3: Run a calculator function. For example, to multiply 2 by 3:​

dfx canister call calc add '(2)'
dfx canister call calc mul '(3)'

Output:

(2 : int)
(6 : int)

Security considerations and best practices​

If you base your application on this example, we recommend you familiarize yourself with and adhere to the security best practices for developing on the Internet Computer. This example may not implement all the best practices.

For example, the following aspects are particularly relevant for this app: