Case statement
A case or switch construct is a conditional control-flow construct that selects a branch or result from alternatives by matching a value or testing conditions.
Learn Go with Pocket-Sized Projects
A switch statement selects among multiple execution branches by evaluating an expression against case conditions.
- How it is used
- Selects language-specific greetings, cache-update actions, and channel responses through readable alternatives.
- How deep it goes
- Explains matching, default handling, implicit breaks, first-case selection, and optional fallthrough without descending into compiler internals.
- Examples
- Demonstrates language greetings, bounded-cache upserts, and channel cancellation in a concurrent maze solver.
- What you can do after
- Build it from scratch in Go to replace repetitive conditional chains with explicit multi-branch logic.
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The Well-Grounded Rubyist, Fourth Edition
A Ruby case statement is a conditional expression that selects execution based on matching a value against alternatives.
- How it is used
- Organizes conditional execution when one value must be compared with several possible alternatives.
- How deep it goes
- Explains syntax, first-match behavior, multiple alternatives, return values, condition-only forms, and internal === dispatch.
- Examples
- Uses user-input prompts, yes-or-no branching, regular-expression input matching, and Ticket objects with custom venue comparison.
- What you can do after
- Apply it via Ruby syntax to branch on values, combine alternatives, return selected expressions, and customize matching with ===.
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Clojure: The Essential Reference
A switch statement is a control-flow construct that selects an execution branch by matching a value against alternative cases.
- How it is used
- Selects a branch quickly when an expression must be matched against fixed alternatives.
- How deep it goes
- Defines inputs, results, exceptions, and literal-test restrictions, then inspects macro expansion and JVM bytecode.
- Examples
- Uses a calculator, quoted-symbol pitfalls, keystroke scoring, and a `cond` benchmark.
- What you can do after
- Apply it in Clojure to dispatch on literal values while avoiding unevaluated-test and duplicate-constant pitfalls.
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100 Java Mistakes and How to Avoid Them
A switch statement is a Java control-flow statement that selects and executes a branch based on the value of an expression.
- How it is used
- Uses case branches to select control flow from a switch expression.
- How deep it goes
- Explains fall-through, prevention patterns, modern syntax, and static-analysis support, while deferring general switch semantics.
- Examples
- Shows button actions, intentional fall-through, character-to-Boolean conversion, and enum-based weekend selection.
- What you can do after
- Diagnose accidental fall-through, write non-falling-through branches, and configure analyzers to recognize intentional flow.
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Kafka Streams in Action, Second Edition
A CASE statement is a SQL conditional expression that evaluates conditions and returns a corresponding result.
- How it is used
- Uses conditional branches in ksqlDB queries to derive values from fields in joined event streams.
- How deep it goes
- Explains branch evaluation through a reward-tier query, without detailing broader SQL expression semantics.
- Examples
- Demonstrates reward-point tiers based on store purchase totals within a customer-rewards stream.
- What you can do after
- Apply it via ksqlDB to derive categorized or tiered output fields from streaming query data.
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Modern C, Third Edition
A switch statement is a C selection statement that transfers control to a matching case or default label based on an expression's value.
- How it is used
- Organizes multiple outcomes when cascaded if-else constructs would be tedious.
- How deep it goes
- Explains selection, jump targets, fall-through, constraints, and declaration hazards, while deferring broader control-flow mechanics.
- Examples
- Uses corvid selection, a count-generated triangle, and character dispatch in a recursive code-indentation parser.
- What you can do after
- Apply switch statements with deliberate fall-through, unique constant cases, default handling, and correctly terminated branches.
D3.js in Action, Third Edition
A switch statement selects and executes code based on which case matches an expression's value.
- How it is used
- Uses conditional branches to choose responsive SVG dimensions and grid columns from the browser width.
- How deep it goes
- Demonstrates `switch (true)` with ranges, `break`, `default`, and Svelte reactivity, without discussing language internals.
- Examples
- Uses screen-width breakpoints to size an SVG and arrange a Van Gogh visualization grid into one, two, or three columns.
- What you can do after
- Apply it via Svelte to recalculate SVG dimensions and layout choices whenever the browser width changes.
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Data-Oriented Programming: Reduce software complexity
A switch statement selects and executes code according to the value of an expression or discriminant.
- How it is used
- Contrasts switch-based data dispatch with object-oriented polymorphism.
- How deep it goes
- Demonstrates type dispatch, validation, and maintenance trade-offs, while stopping short of general switch semantics.
- Examples
- Uses dog, cat, and cow maps whose greetings are selected by their type fields.
- What you can do after
- Evaluate centralized case dispatch against separate polymorphic implementations and add validation for map-shaped inputs.
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Modern C
A switch statement is a C selection construct that chooses among multiple execution paths based on the value of an expression.
- How it is used
- Performs multiple selection when a Boolean if decision or an if-else cascade is insufficient.
- How deep it goes
- Explains syntax, jump-target semantics, break termination, fallthrough, default, and integer constant case restrictions.
- Examples
- Uses character classification, puts calls, and a numeric fallthrough example that produces progressively shorter output.
- What you can do after
- Builds multiple-selection control flow with case, default, and break, and recognizes intentional or accidental fallthrough.
Related concepts
- conditional logicalternative to · Conditional logic is a programming technique that selects execution paths, actions, or result values according to evaluated conditions.
- break statementuses · A break statement terminates the nearest supported enclosing loop, switch, or similar control construct and transfers control to the following statement.
- when expressionalternative to · A when expression is a Kotlin multi-branch conditional expression that selects a result by matching conditions or a subject value against alternatives.
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