What is the difference between fmt.Println and log.Println in Go?

Question

Accepted Answer

**fmt.Println** — stdout, no metadata. **log.Println** — stderr, adds timestamp.

**fmt.Println:**
- Writes to stdout.
- No timestamp.
- No file info.
- For user output.

```go
fmt.Println("Hello")
// Output: Hello
```

**log.Println:**
- Writes to stderr.
- Adds timestamp.
- Adds file and line.
- For debugging/logging.

```go
log.Println("Hello")
// Output: 2024/01/15 10:30:45 Hello
```

**Key differences:**
- **fmt** — stdout, no metadata.
- **log** — stderr, with metadata.
- **fmt** — user output.
- **log** — debugging.

**log flags:**
```go
log.SetFlags(log.Ldate | log.Ltime | log.Lshortfile)
```

Go: What is the difference between fmt.Println and log.Println in Go?