just see the code:(so simple that I can't believe myself)
package log
import "fmt"
func P(format string,a ...interface{}){
fmt.Printf(format,a)
}
when called somewhere like this :
log.P("%s,%s,%d","","",0)
I got error:
[ %!s(int=0)],%!s(MISSING),%!d(MISSING)
BUT if I call fmt.Printf directly like this:
fmt.Printf("%s,%s,%d","","",0)
It works perfectly,just perfectly (of course,as basic use of fmt).
So the Question is:
FYI:
I believe it's pretty simple ,but I just can't find an answer by google, never ever someone dropped in the hell ?
Or maybe I just dont know how to ask,so I put pure code above.
Or just I'm a super fool this time?
I signed up stackoverflow today for an answer to this. Let me know what's wrong with me. As soon...
It is just a little mistake. You are calling fmt.Printf with a as a single argument, while it is not. You need to pass it as a variadic argument.
package main
import (
"fmt"
)
func P(format string, a ...interface{}) {
fmt.Printf(format, a)
}
func P2(format string, a ...interface{}) {
fmt.Printf(format, a...)
}
func main() {
P("%s,%s,%d", "", "", 0)
fmt.Println()
P2("%s,%s,%d", "hello", "world", 0)
}
You can read about variadic parameters here.
You need to pass a to Printf as variadic and to convert an array to variadic, you need to follow this notation:
func P(format string, a ...interface{}){
fmt.Printf(format, a...)
}
The Go Programming Language Specification
Passing arguments to ... parameters
If f is variadic with final parameter type ...T, then within the function the argument is equivalent to a parameter of type []T. At each call of f, the argument passed to the final parameter is a new slice of type []T whose successive elements are the actual arguments, which all must be assignable to the type T. The length of the slice is therefore the number of arguments bound to the final parameter and may differ for each call site.