fmtPrintf

fmt.Printf is a function in the Go standard library’s fmt package that formats its arguments according to a format specifier and writes the result to standard output. It is widely used for console output and quick debugging, and it supports a broad set of formatting verbs, flags, width, and precision options.

The function signature is: func Printf(format string, a ...interface{}) (n int, err error). It writes to os.Stdout by default and returns the number of bytes written and any error encountered. fmt.Printf is a convenience wrapper around Fprintf(os.Stdout, format, a...). Its behavior is determined by the format string and the supplied arguments, which can be any values, with the actual formatting governed by the verbs defined in the fmt package.

Formatting verbs and capabilities: The format string can contain verbs such as %v (default formatting), %+v (adds field names for structs), %#v (Go-syntax representation), %T (type), %d, %f, %s, %q, %x, %p, %c, and more. Flags, width, and precision can modify output (for example, %8.2f or %-10s). Custom types can implement the Stringer interface to control their textual representation, or the Formatter interface for custom formatting. The fmt package also provides related functions like fmt.Sprintf (which returns a string) and fmt.Fprintf (which writes to a specified io.Writer).

Usage notes: fmt.Printf is suitable for inline, immediate output. For string construction without printing, use fmt.Sprintf; for writing to a specific destination, use fmt.Fprintf. Example: fmt.Printf("Hello, %s\n", name). The function is a core tool for formatted output in Go programs.