What is running here: Go
This Go page is a scratchpad, not a ceremony. Paste the smallest useful program, run it from the main editor, and keep the output panel close while you make changes.
Runs Go via Piston from main.go, using the current Go runtime available in the execution image. That matters because the runtime boundary explains most surprises: packages, files, network access, and server state are different once code leaves a full local project.
We like this page for goroutine sketches, slices, maps, structs, JSON encoding, and competitive-programming style input. Go is one of the best languages for this kind of runner because small programs stay readable.
Execution flow
- Start with the smallest Go snippet that can show the behavior.
- Add input only when the program reads it. Empty STDIN is a valid test case.
- Press Run, inspect stdout and stderr, then change one line. That rhythm keeps accidental fixes from hiding the real bug.
The mechanics are simple. We keep the run cycle compact because this page is meant to answer one question at a time, not manage a full project tree.
That style also makes the result easier to share. A reader can scan a short Go snippet, run it, and see the same error without first recreating your directory structure or guessing which dependency you forgot to mention.
Use the sample deliberately
The saved example below is intentionally left unchanged. Run it once as written, then make a small edit and run it again; that gives you a known-good baseline before you test your own idea.
package main
import "fmt"
func main() {
var name string
fmt.Scanln(&name)
fmt.Println("Hello,", name, "- welcome to Go!")
}The next preserved block belongs to the same example. Keep it nearby when you are comparing input, output, or the shape of the result. Small examples expose mistakes quickly.
Hello, Alice - welcome to Go!After the sample works, try one edge case that exercises the page's limits. The file still needs package main and a main function when you want an executable program. That single change often teaches more than pasting a large program and trying to guess which part failed.
Tradeoffs
This page is strongest when the problem is small and visible. It is weakest when the problem depends on module resolution, cgo, network services, and timing-sensitive concurrency tests. Two caveats.
- Do not paste secrets, tokens, private URLs, or customer data.
- The environment is intentionally constrained, so a snippet that works here still deserves a local check when compiler flags, packages, server state, or exact versions matter.
- Timeouts are normal for runaway loops. They protect the shared runner.
We deliberately keep the sandbox narrow. That makes the output easier to trust for goroutine sketches, slices, maps, structs, JSON encoding, and competitive-programming style input, while making it clear when you have outgrown the page.
One practical test: if you cannot explain the snippet in one sentence, split it. The runner is happiest when each run answers a single question, and you will be happier too when the error message points at one idea instead of a pile of guesses.
Short answers
This FAQ is intentionally mixed: short answers for quick checks, longer notes where Go has environment traps. Scan it once before assuming the runner and your local setup behave the same.
Is Go compiled or interpreted?
Go is compiled. The Go toolchain turns source code into machine code for the target platform. For a simple local file, go run main.go compiles and runs it in one step, while go build creates an executable. This page keeps that workflow small so you can focus on syntax and output. For example, go run main.go is the simplest local check for a one-file program.
Does Go compile to machine code?
Yes, Go normally compiles to native machine code. The final executable includes the Go runtime pieces it needs, such as garbage collection support. That is one reason Go programs are easy to distribute. Online, you should still treat performance numbers as rough, because the sandbox is not your machine. A runnable Go file still needs package main and a main function, even when the example is only a few lines long.
How to compile a Go program?
Locally, use go run main.go while you are experimenting and go build when you want an executable. A runnable file needs package main and a main function. If your code uses modules or several files, test it in a local folder rather than pasting pieces into an online editor. For example, go run main.go is the simplest local check for a one-file program.
What could go wrong during Go compilation?
Common Go compile problems include unused imports, unused variables, wrong package names, missing main functions, and type mismatches. Go reports these early, which can feel strict but keeps programs tidy. If the error looks noisy, fix the first one first; later messages often disappear after that. A runnable Go file still needs package main and a main function, even when the example is only a few lines long.
How to compile Go with GCC?
Most Go code is compiled with the standard Go toolchain, not GCC. There is gccgo, a GCC frontend for Go, but it is not the normal path for most developers. If you are learning Go, start with go run and go build from the official Go tools. For example, go run main.go is the simplest local check for a one-file program.
Version?
This page runs Go through Piston using main.go; the wildcard version means the runner supplies its available go runtime. I would treat that as good enough for syntax checks, but not as a promise about your production version. If a feature depends on a release, run the same snippet locally and check the official release notes. Version mismatches usually show up as syntax errors, missing APIs, or slightly different standard-library behavior.
Can I use packages with Go?
Assume package installs are not available here unless the page already loads a library for the demo. That keeps the run predictable and quick. If your example needs a package manager, create a local project and add the dependency there, then use this page only for the small language part. For online testing, replace the dependency call with a tiny mock value and test your own logic around it.
Show me stdin.
Use the STDIN box for the text your program would normally read from the terminal. Put one input value per line. For example, enter Alice on the first line and 42 on the second, then read two values in your code. If parsing fails, test one line first before adding more cases. This is especially helpful for coding-challenge style problems where input shape causes most mistakes.
Why did my run stop?
The runner may stop code that loops too long, waits for input you did not provide, or tries work outside the sandbox. Start by shrinking the input and adding one print statement before the slow section. If the smaller case finishes, the original program probably has a loop, scale, or environment problem. For example, go run main.go is the simplest local check for a one-file program.
How to run Go code online?
Paste your Go program in the editor - include the package main line and a func main. If the program reads from stdin, put each input line in the STDIN box. Click Run. Compilation errors and program output both appear in the Output panel on the right.
When this page helps
Use it when you are stuck on someone else's machine, teaching a small concept, or separating a language question from a project question. No ceremony.
It also works well as a note-taking tool: paste the final snippet into your lesson, issue, or commit message after you have proved it in the runner.
Keep the example slightly smaller than feels natural. That sounds fussy, but it prevents a common debugging mistake: changing five pieces of code, getting a different result, and no longer knowing which piece mattered.
References
Reference pages are better than folklore when an error message gets specific. Start with official docs, then use tutorials for context once the rule is clear.