HTTP log middleware in Go can record request methods, paths, client IP and time-consuming. 1. Use http.HandlerFunc to wrap the processor, 2. Record the start time and end time before and after calling next.ServeHTTP, 3. Get the real client IP through r.RemoteAddr and X-Forwarded-For headers, 4. Use log.Printf to output request logs, 5. Apply the middleware to ServeMux to implement global logging. The complete sample code has been verified to run and is suitable for starting a small and medium-sized project. The extension suggestions include capturing status codes, supporting JSON logs and request ID tracking.

Go's switch statement will not be executed throughout the process by default and will automatically exit after matching the first condition. 1. Switch starts with a keyword and can carry one or no value; 2. Case matches from top to bottom in order, only the first match is run; 3. Multiple conditions can be listed by commas to match the same case; 4. There is no need to manually add break, but can be forced through; 5.default is used for unmatched cases, usually placed at the end.

Go generics are supported since 1.18 and are used to write generic code for type-safe. 1. The generic function PrintSlice[Tany](s[]T) can print slices of any type, such as []int or []string. 2. Through type constraint Number limits T to numeric types such as int and float, Sum[TNumber](slice[]T)T safe summation is realized. 3. The generic structure typeBox[Tany]struct{ValueT} can encapsulate any type value and be used with the NewBox[Tany](vT)*Box[T] constructor. 4. Add Set(vT) and Get()T methods to Box[T] without

Goprovidesbuilt-insupportforhandlingenvironmentvariablesviatheospackage,enablingdeveloperstoread,set,andmanageenvironmentdatasecurelyandefficiently.Toreadavariable,useos.Getenv("KEY"),whichreturnsanemptystringifthekeyisnotset,orcombineos.Lo

Run the child process using the os/exec package, create the command through exec.Command but not execute it immediately; 2. Run the command with .Output() and catch stdout. If the exit code is non-zero, return exec.ExitError; 3. Use .Start() to start the process without blocking, combine with .StdoutPipe() to stream output in real time; 4. Enter data into the process through .StdinPipe(), and after writing, you need to close the pipeline and call .Wait() to wait for the end; 5. Exec.ExitError must be processed to get the exit code and stderr of the failed command to avoid zombie processes.

In Go, to break out of nested loops, you should use labeled break statements or return through functions; 1. Use labeled break: Place the tag before the outer loop, such as OuterLoop:for{...}, use breakOuterLoop in the inner loop to directly exit the outer loop; 2. Put the nested loop into the function, and return in advance when the conditions are met, thereby terminating all loops; 3. Avoid using flag variables or goto, the former is lengthy and easy to make mistakes, and the latter is not recommended; the correct way is that the tag must be before the loop rather than after it, which is the idiomatic way to break out of multi-layer loops in Go.

Usecontexttopropagatecancellationanddeadlinesacrossgoroutines,enablingcooperativecancellationinHTTPservers,backgroundtasks,andchainedcalls.2.Withcontext.WithCancel(),createacancellablecontextandcallcancel()tosignaltermination,alwaysdeferringcancel()t

The answer is: Go applications do not have a mandatory project layout, but the community generally adopts a standard structure to improve maintainability and scalability. 1.cmd/ stores the program entrance, each subdirectory corresponds to an executable file, such as cmd/myapp/main.go; 2.internal/ stores private code, cannot be imported by external modules, and is used to encapsulate business logic and services; 3.pkg/ stores publicly reusable libraries for importing other projects; 4.api/ optionally stores OpenAPI, Protobuf and other API definition files; 5.config/, scripts/, and web/ store configuration files, scripts and web resources respectively; 6. The root directory contains go.mod and go.sum