#GoLang

Last updated    - V4 (14-Sep-2025)

Level Subtopic Topics (Grouped) Basic Language Fundamentals History & Features of Go, Go Toolchain (go run, go build, go mod), Workspaces & Modules Data Types & Variables Primitive Types (int, float, string, bool), Constants (iota), Type Inference (:=) Control Structures if/else, switch, loops, break & continue, Labels Functions Function Declaration, Multiple Return Values, Named Returns, Variadic Functions Collections Arrays, Slices, Maps, Range Iteration Pointers & Structs Pointers Basics, Structs, Struct Embedding, Methods with Structs Intermediate Interfaces & Polymorphism Interface Basics, Empty Interface (interface{}), Type Assertions, Duck Typing Error Handling error type, Custom Errors, Panic & Recover, Error Wrapping (errors.Is, errors.As) Concurrency (Basics) Goroutines, Channels, Buffered vs Unbuffered, select statement Standard Library Essentials fmt, strings, strconv, time, math/rand, File I/O Testing testing package, Table-driven tests, Mocks & Stubs, Coverage Packages & Imports Creating Packages, Visibility (Exported vs Unexported), Dependency Management with go mod Advanced Concurrency (Advanced) Mutex & RWMutex, WaitGroups, Condition Variables, Atomic Operations, Worker Pools Context Management context.Background, context.WithCancel, Deadlines & Timeouts Reflection & Generics reflect package, Type Introspection, Generics in Go 1.18+ Networking net/http, TCP/UDP Servers, gRPC with Go, REST APIs JSON & Serialization encoding/json, Struct Tags, encoding/xml, protobuf Go Routines Patterns Fan-in, Fan-out, Pipeline Pattern, Cancellation Pattern Error Handling (Advanced) Sentinel Errors, Error Propagation, Error Wrapping Best Practices File & OS Interaction File Permissions, Directory Traversal, Environment Variables, OS Signals Expert Go Runtime & Memory Garbage Collection, Escape Analysis, Stack vs Heap Allocation, Memory Profiling Compiler & Internals SSA Form, Go Assembly, Optimizations, go build flags Advanced Concurrency Actor Model, CSP Model, Lock-Free Programming Performance Tuning Benchmarking with testing.B, Profiling with pprof, Reducing Allocations System Programming CGO Basics, Interfacing with C, Syscalls Design Patterns in Go Singleton, Factory, Observer, Strategy, Adapter in Go idioms Distributed Systems with Go Microservices, Message Queues (Kafka/NATS), Service Discovery Cloud & DevOps Dockerizing Go Apps, Kubernetes Operators in Go, CI/CD with Go, Observability (Prometheus, OpenTelemetry) Security in Go TLS/SSL, JWT Authentication, Secure Coding, Static Analysis (gosec) Large Scale Go Monorepos, Code Organization, Package Design Principles, Best Practices for Maintainability

1. Basics of Go

1. What is Go and why was it developed?
2. What are the main features of Go?
3. Explain Go?s compilation model.
4. What is the difference between Go and other languages like Java/C++?
5. How do you install Go on your system?
6. Explain GOPATH and GOROOT.
7. How do you write your first Go program?
8. What are Go?s primitive data types?
9. Explain variable declaration in Go.
10. Difference between var and := in Go.
11. What are constants in Go and how do you declare them?
12. Explain type inference in Go.
13. How do you declare multiple variables in one line?
14. Explain zero values in Go.
15. What is a rune in Go?
16. Difference between string and byte types.
17. How do you use basic arithmetic operators in Go?
18. How does Go handle boolean expressions?
19. What are pointers in Go?
20. How do you use pointers safely in Go?
21. Explain type conversion in Go.
22. What is the difference between value types and reference types?
23. How do you handle comments in Go?
24. Explain basic input/output in Go.
25. How do you format code in Go?

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2. Control Flow & Functions

1. Explain if, else if, else in Go.
2. How do you use switch statements in Go?
3. What is the use of fallthrough in switch cases?
4. Explain loops in Go (for loop variations).
5. How does Go handle infinite loops?
6. What are break and continue in Go?
7. How do you write functions in Go?
8. Difference between named and unnamed return values.
9. What is a variadic function?
10. How do you pass parameters to functions in Go?
11. Difference between pass by value and pass by reference.
12. How do you return multiple values from a function?
13. Explain anonymous functions in Go.
14. What is a closure in Go?
15. How do you define recursive functions in Go?
16. Difference between function and method in Go.
17. What is defer keyword and how is it used?
18. Explain panic and recover.
19. How do you handle errors using functions in Go?
20. What are function types in Go?
21. How do you pass a function as a parameter?
22. How do you use init() function?
23. What is the significance of main() function?
24. How do you document functions in Go?
25. Best practices for writing functions in Go.

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3. Structs, Interfaces & Methods

1. What is a struct in Go?
2. How do you declare and initialize a struct?
3. How do you access struct fields?
4. What are embedded structs?
5. How do you create methods on structs?
6. Difference between value receiver and pointer receiver.
7. What are interfaces in Go?
8. How do you define an interface?
9. Difference between implicit and explicit interface implementation.
10. How does Go achieve polymorphism?
11. What is type assertion in Go?
12. How do you check type compatibility using interfaces?
13. Explain empty interface interface{}.
14. How do you use interface composition?
15. What are interface methods?
16. Difference between struct embedding and interface embedding.
17. How do you implement multiple interfaces?
18. How do you pass structs to functions?
19. What is the difference between a slice of structs and slice of pointers to structs?
20. How do you compare structs in Go?
21. Explain method promotion in embedded structs.
22. How do you define constants inside structs or interfaces?
23. How do you prevent struct modification from outside?
24. Explain the difference between concrete types and interface types.
25. Best practices for structs and interfaces in Go.

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4. Arrays, Slices & Maps

1. What is an array in Go?
2. How do you declare and initialize arrays?
3. Difference between array length and capacity.
4. How do you iterate over arrays?
5. What is a slice in Go?
6. How do you create slices from arrays?
7. Difference between slices and arrays.
8. Explain slice capacity and length.
9. How do you append elements to a slice?
10. How do you copy slices?
11. What is the difference between nil slice and empty slice?
12. How do you delete an element from a slice?
13. How do slices share underlying arrays?
14. What are multi-dimensional slices?
15. What is a map in Go?
16. How do you declare and initialize maps?
17. How do you access map elements?
18. How do you delete keys from a map?
19. What happens if you access a non-existing key in a map?
20. How do you iterate over maps?
21. How do you check existence of a key in a map?
22. Explain map reference semantics.
23. How do you create nested maps?
24. Best practices for using slices and maps.
25. Difference between slices, arrays, and maps.

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5. Concurrency & Goroutines

1. What is a goroutine in Go?
2. How do you create a goroutine?
3. Difference between goroutine and thread.
4. What is the role of Go scheduler?
5. What are channels in Go?
6. How do you declare and use channels?
7. Explain buffered vs unbuffered channels.
8. How do you synchronize goroutines using channels?
9. What is select statement in Go?
10. How do you use close() on channels?
11. What are direction-specific channels?
12. How do you implement worker pools in Go?
13. Explain race conditions and how to avoid them.
14. How do you use sync.Mutex in Go?
15. Explain sync.WaitGroup.
16. What is sync.Once and how is it used?
17. How do you prevent deadlocks in Go?
18. Explain context package in concurrency.
19. Difference between goroutines and OS threads.
20. How do you communicate between goroutines safely?
21. Explain fan-in and fan-out patterns.
22. How do you implement timeouts with channels?
23. How do you monitor goroutines for leaks?
24. Best practices in Go concurrency.
25. What are atomic operations in Go?

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6. Error Handling & Testing

1. How does Go handle errors?
2. Difference between panic and error.
3. How do you create custom errors?
4. What is errors.New()?
5. How do you wrap errors in Go 1.13+?
6. Explain fmt.Errorf with %w.
7. How do you check error type using errors.As()?
8. What is errors.Is() used for?
9. How do you propagate errors up the call stack?
10. Difference between handling errors and panicking.
11. How do you test Go programs?
12. Explain table-driven tests.
13. How do you use testing package?
14. How do you benchmark functions in Go?
15. How do you skip tests conditionally?
16. How do you use subtests in Go?
17. How do you mock dependencies for testing?
18. How do you test concurrency in Go?
19. Explain code coverage in Go tests.
20. How do you handle temporary files in tests?
21. How do you use Go test flags?
22. How do you run tests in parallel?
23. What is TestMain function in Go?
24. Best practices for error handling in Go.
25. Best practices for writing tests in Go.

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7. Packages & Modules

1. How do you organize code using packages?
2. Difference between standard library and custom packages.
3. How do you import packages in Go?
4. What is Go module system?
5. How do you create a Go module?
6. How do you add dependencies in Go modules?
7. Explain go.mod file.
8. Explain go.sum file.
9. How do you upgrade dependencies in Go modules?
10. How do you remove unused dependencies?
11. What are semantic versioning rules in Go modules?
12. How do you handle private modules?
13. How do you vendor dependencies?
14. How do you manage module proxies?
15. Explain replace directive in go.mod.
16. How do you handle version conflicts?
17. How to test modules independently?
18. Difference between GOPATH and Go modules.
19. How do you use build constraints in packages?
20. How do you use package-level documentation?
21. Best practices for naming packages.
22. How do you structure large Go projects?
23. How do you publish Go modules?
24. How do you ensure module compatibility?
25. How do you import sub-packages?

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8. File I/O & Networking

1. How do you read and write files in Go?
2. Explain os package usage.
3. How do you use io and ioutil packages?
4. Difference between Read and ReadAll.
5. How do you append to files in Go?
6. How do you handle directories in Go?
7. How do you handle file permissions?
8. How do you work with CSV files in Go?
9. How do you parse JSON files in Go?
10. How do you encode/decode JSON in Go?
11. How do you handle HTTP requests in Go?
12. Explain net/http package usage.
13. How do you create HTTP server in Go?
14. How do you make HTTP client requests in Go?
15. How do you use URL encoding in Go?
16. How do you handle query parameters in HTTP requests?
17. How do you handle HTTP headers in Go?
18. How do you implement REST APIs in Go?
19. How do you handle TCP/UDP connections?
20. How do you use net package for sockets?
21. How do you implement TLS in Go?
22. How do you use context in networking?
23. How do you stream large files over HTTP?
24. How do you handle timeouts in HTTP requests?
25. Best practices in file I/O and networking.

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9. Reflection & Unsafe

1. What is reflection in Go?
2. How do you inspect types at runtime?
3. How do you access struct fields using reflection?
4. How do you call methods dynamically using reflection?
5. How do you modify struct fields at runtime?
6. Difference between type assertion and reflection.
7. How do you iterate over struct fields using reflection?
8. How do you use reflect.Type and reflect.Value?
9. How do you get method names of a struct?
10. How do you use tags in struct fields?
11. What is the unsafe package in Go?
12. How do you use pointers in unsafe?
13. What are risks of using unsafe package?
14. How do you convert between pointer types using unsafe?
15. How do you access memory directly using unsafe?
16. Difference between uintptr and unsafe.Pointer.
17. How do you align memory using unsafe?
18. How do you use reflect with unsafe?
19. How to optimize performance using unsafe?
20. How do you check type of interface at runtime?
21. How to call functions dynamically?
22. How to validate struct types at runtime?
23. Best practices for reflection in Go.
24. Best practices for unsafe usage.
25. Common pitfalls using reflection and unsafe.

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10. Advanced Go Concepts & Best Practices

1. Explain Go runtime and scheduler.
2. Difference between Go runtime and OS threads.
3. How does garbage collection work in Go?
4. How do you profile Go programs?
5. How do you optimize memory usage?
6. How do you handle large data efficiently?
7. Explain Go compiler optimizations.
8. How do you handle configuration in Go apps?
9. How do you structure microservices in Go?
10. How do you implement logging in Go?
11. How do you handle environment variables?
12. How do you handle secrets safely?
13. How do you implement caching in Go?
14. How do you implement metrics in Go apps?
15. How do you use Prometheus with Go?
16. How do you implement structured logging?
17. How do you deploy Go applications?
18. How do you build Docker images for Go apps?
19. How do you handle CI/CD for Go applications?
20. How do you handle versioning in Go modules?
21. Best practices for error handling in Go.
22. Best practices for concurrency in Go.
23. Best practices for writing maintainable Go code.
24. How do you handle panics in production apps?
25. How do you write idiomatic Go code?