Conditionals in Go

Complete guide to Go conditionals: if, else, else if, switch, logical conditions, conditions must be bool, guard clauses, and best practices.

Introduction to Conditionals

Conditionals let a program run different code based on boolean expressions. They are the basis of control flow and logic in Go.

1. What are Conditionals?

Conditionals run code only when a condition is true.

if / else / else if

Use if for a single branch, if/else for two branches, and else if for multiple branches. Conditions are checked from top to bottom.

1. Simple if Statement

Run code only when the condition is true.

2. if / else Statement

Choose between two paths.

3. else if Chain

Handle multiple conditions in order.

Conditions Must Be bool

Go does not treat other types as true or false. The condition in an if must be a bool. Use explicit comparisons (e.g. len(s) > 0, n != 0).

1. No Automatic Conversion

You cannot use an int or string directly as a condition. Compare explicitly.

2. Explicit Checks for "Has Value"

For strings, slices, or pointers, check length or nil explicitly.

Logical Conditions

Use && when all conditions must be true, || when at least one must be true, and ! to negate a boolean.

1. Logical AND (&&)

Both conditions must be true.

2. Logical OR (||)

At least one condition must be true.

3. Logical NOT (!)

Invert a boolean condition.

Choosing Values with if/else

You can define a generic function Conditional[T] that returns one of two values based on a boolean. For multiple branches, use if/else or switch.

1. Generic Conditional Helper

A generic function that returns one of two values based on the condition. Both values must be the same type.

2. Two-Way Choice with if/else

Alternatively, assign in each branch without a helper.

3. Multiple Branches (else if)

Choose among several values with else if. The Conditional helper only handles two values.

switch Statement

switch is useful when one expression is compared to several constant values. In Go, cases break automatically; use fallthrough to continue to the next case.

1. Basic switch

Match the value against case literals or constants.

2. Fall-through

Use the fallthrough keyword to run the next case as well.

Nested and Ladder if-else

Put an if inside another when a condition depends on a previous one. Use an if / else if / else ladder when checking several conditions in sequence.

1. Nested if-else

An if block inside another if block.

2. Ladder if-else

Multiple else if branches in sequence.

Guard Clauses

Handle invalid or edge cases at the start and return (in functions) or continue (in loops). This keeps the main path clear and reduces nesting.

1. Guard Clause in Functions

Return early on invalid input or preconditions.

2. Guard Clause in Loops

Use continue to skip the rest of the iteration.

Best Practices

Good conditional practices reduce bugs, improve readability, and make code easier to maintain and extend.

1. Recommended Best Practices

Guidelines for writing better conditionals.