Solidity Tutorial: All About Conditionals

Understand through Smart contract examples

photo by Alex Padurariu on Unsplash

Everyone writing code on a daily basis knows what a if / else statement is. But still, since we are in the “All About Solidity” article series, we’ll cover everything about the Solidity smart contract language!

No bent rules! We cannot omit conditionals!

In today’s article, we will still cover the basics of conditionals in Solidity, and some of their variants.

But instead of re-explaining if statements all over again from scratch, we will the Solidity code of 4 very popular smart contract projects: CryptoKitties, BarnBridge, Sablier, and LUKSO.

So we can as well learn and understand how some popular smart contracts work and increase our curiosity.

Table of Contents

Overview
Example 1 — CryptoKitties
  Basic if statement (one condition)
  Either one condition or another with ||
  Use a variable as a condition
Example 2 — BarnBridge
  Concatenating multiple conditions with &&
  if { … } else { … }
Example 3 — Sablier
  One line if statements
  What else can be written inside if statements in Solidity?
Example 4 — LUKSO
  omitting curly braces
Final Notes on Solidity conditionals
References

Overview

Conditionals in Solidity follow the basic constructs of other programming languages:

• a condition is wrapped inside the brackets of an if statement.
• if the condition evaluates to true, the code inside the curly brackets runs.
• if the condition evaluates to false, the program execution jumps to the next statement after the closing bracket }.

Nothing new here! But let’s see in practice with some real Solidity code currently running on mainnet!

Example 1 — CryptoKitties