Control Statements in Go

This module covers the essential control flow constructs in Go: conditional statements, loops, and switch-case. Mastery of these is fundamental for writing logical and efficient Go programs.

1. Conditional Statements (if-else)

Conditional statements allow your program to make decisions based on conditions. In Go, the if statement is simple and does not require parentheses around the condition.

Syntax

if condition {
    // code
} else if anotherCondition {
    // code
} else {
    // code
}

Why Go's if-else?

• No parentheses required, making code less cluttered.

• You can declare variables in the if statement, scoped only to that block:

  if x := compute(); x > 10 {
      // use x
  }

• Encourages short, readable blocks.

Real-World Analogy

Think of if-else as a series of road signs: "If the road is closed, take the detour; else if there's traffic, take the highway; else, continue straight."

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2. Loops

Go has only one looping construct: the for loop. It is versatile and can be used as a traditional for, a while, or an infinite loop.

Classic for

for i := 0; i < 5; i++ {
    // ...
}

While-style

for condition {
    // ...
}

Infinite loop

for {
    // ...
    if done {
        break
    }
}

Why only for?

• Simplifies the language and reduces confusion.

• All loop patterns are possible with just for.

Best Practices

• Use break to exit a loop early.

• Use continue to skip to the next iteration.

• Avoid deeply nested loops for readability.

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3. Switch Statement

The switch statement in Go is a powerful alternative to long if-else chains. It can be used with or without a condition.

Syntax

switch variable {
case value1:
    // ...
case value2:
    // ...
default:
    // ...
}

Unique Features

• Cases do not "fall through" by default (unlike C/C++/Java). Use fallthrough explicitly if needed.

• Can be used without a condition for more complex logic.

• Multiple values can be matched in a single case.

Real-World Analogy

A switch is like a train station: depending on the track (case), the train (program) goes in a different direction.

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4. Best Practices

• Prefer switch over long if-else chains for clarity.

• Use short variable declarations in if/switch when possible.

• Avoid infinite loops unless necessary (e.g., servers).

• Keep control flow blocks short and focused.

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Why Go's Control Flow?

• Go’s minimalism means fewer ways to do the same thing, making codebases more uniform.

• The lack of exceptions (no try/catch) means errors are handled explicitly, usually with return values.

• Encourages clear, linear code that is easy to follow and maintain.

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Practice & Conceptual Questions

1. Write a program to classify a grade into A/B/C/Fail using if-else.

2. Check if a number is positive, negative, or zero.

3. Print the factorial of a number using a loop.

4. Print the Fibonacci series up to N terms.

5. Sum even numbers from 1 to 50 using continue.

6. Create a switch case to identify days from 1–7.

7. Use fallthrough to group weather types: Sunny, Cloudy, Rainy.

8. Replace if-else ladder for marks grading with switch.

9. What are the benefits of using switch over multiple if-else statements?

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Further Reading

• Go by Example: If/Else

• Go by Example: For

• Go by Example: Switch