Class-16

Class 16 – Blockchain & Smart Contract Basics

Class Slides: Class 16.1

This lecture introduces Solidity conditional statements and loops, explaining how they control the flow of execution in smart contracts. Understanding these structures is essential for writing efficient and flexible Solidity programs.

Key Topics Covered:

1. Solidity Contract Structure
A Solidity contract consists of various components, including:

• State Variables – Store contract data.
• Function Definitions – Define behavior and logic.
• Enumerations (Enums) – Define user-defined types.
• Structures (Structs) – Organize related data.
• Modifiers – Control function execution.
• Events – Log contract activity.

2. Comparison Operators in Solidity

• Used to compare two values and return a Boolean (true or false).
• Examples include:
  • == (equal to)
  • != (not equal to)
  • > (greater than)
  • < (less than)
  • >= (greater than or equal to)
  • <= (less than or equal to)

3. Logical Operators in Solidity

• Used to combine multiple conditions within conditional statements.
• Types of logical operators:
  • && (AND): Returns true if both conditions are true.
  • || (OR): Returns true if at least one condition is true.
  • ! (NOT): Inverts a Boolean value (true becomes false, and vice versa).

4. Conditional Statements in Solidity

• if Statement: Executes a block of code if a condition is true.
• if-else Statement: Specifies a block of code to execute when the condition is false.
• if-else if-else Statement: Evaluates multiple conditions sequentially.

Example of an if-else statement in Solidity:

uint age = 18;
if (age > 18) {
// Execute this code if age is greater than 18
} else {
// Execute this code if age is not greater than 18
}

5. Solidity Loops

• Loops are used when a certain task needs to be executed repeatedly.
• Types of loops in Solidity:
  • While Loop: Executes while a specified condition is true.
  • Do-While Loop: Similar to a while loop but ensures execution at least once.
  • For Loop: Repeats a block of code for a specific number of iterations.

Example of a for loop in Solidity:

for (uint i = 0; i < 5; i++) {
// Executes 5 times
}