fmt.Scanf(%d%s%d)

[Bardia Jedi]

Hi I'm trying to read an basic equation and output result! here my code 

package main 

import "fmt"

func main (){

fmt.Print("input ekvation: ")

var a, b int

var s rune

fmt.Scanf("%d %5v %d", &a, &s, &b)

fmt.Println (a, string(s), b)

}

the idea is that the user input an equation and the program separtas the int and the operations and acts accordingly 

e.g. 

1+2 

set 1 to int a 

+ is a char (rune) so it stors it as rune

2 is an integer 

so throw some logic is output 3

----------

now the problem is that scanf reads evrything after the %s!

anyideas?

  

[Dave Cheney]

fmt.Scanf and friends return an error. What does is say when you run your program. 

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[Bardia Jedi]

it able to compile and it output 

1 +2 0

were +2 is an string 

I have try it w/ runes and bytes  now when i do that is gives me value 0 witch means that it's not reading anything

[Kyle Lemons]

Scanf, like its C counterpart, expects space separated tokens.

http://play.golang.org/p/Jmw7JGyu56

For expression parsing you'll probably need your own tokenizer.

  

--

[Bardia Jedi]

ok that work but Go Playground doesn’t support keyboard input and i want the user to input a equation, so I started coding and got this:

package main

import "fmt"

func main () {

    var a , b  int
    var op, s  string
    fmt.Scanln( &s)
    fmt.Fscanf(s ,"%d %s %d", &a ,&op ,&b)
    fmt.Println(a, b , op)
    fmt.Println(s)
}

and here is the problem I'm having
1- fmt.Scanln dose not read the line it only reads till the \n  -> this most be a bug right!?
2- fmt.FscanF doesn't accepts the string 's'

 

On Monday, February 4, 2013 4:09:24 PM UTC+1, Bardia Jedi wrote:

[Kyle Lemons]

fscanf was just there so that you wouldn't think you had to read it in all at once and use sscanf.  Use Fscanf(os.Stdin or Scanf

--

[minux]

On Wed, Feb 6, 2013 at 6:44 AM, Bardia Jedi <bardi...@gmail.com> wrote:

ok that work but Go Playground doesn’t support keyboard input and i want the user to input a equation, so I started coding and got this:

package main

import "fmt"

func main () {

    var a , b  int
    var op, s  string
    fmt.Scanln( &s)
    fmt.Fscanf(s ,"%d %s %d", &a ,&op ,&b)
    fmt.Println(a, b , op)
    fmt.Println(s)
}

and here is the problem I'm having
1- fmt.Scanln dose not read the line it only reads till the \n  -> this most be a bug right!?

what do you mean? fmt.Scanln(&s) should work as documented.

2- fmt.FscanF doesn't accepts the string 's'

use fmt.Sscanf for strings, Fscanf is for file like objects (io.Reader).

[Bardia Jedi]

minux! -> sorry wrong char what I should have said was " "
e.g.
var s string
fmt.Print("input: ")
fmt.Scanln(&s)
fmt.Println(s)
---------------------------
input: hello world
hello

do u see am I doing something wrong!

////////////////////////7
kyle!
thak for the help I understand it better now.
so i gess there is on built in command to let the user not worry about space between integer and operator

/thx Bardia Jedi 

[minux]

On Thursday, February 7, 2013, Bardia Jedi wrote:

minux! -> sorry wrong char what I should have said was " "
e.g.
var s string
fmt.Print("input: ")
fmt.Scanln(&s)
fmt.Println(s)
---------------------------
input: hello world
hello

do u see am I doing something wrong!

please read docs for fmt.Scan and you will understand Scanln's behavior:
http://golang.org/pkg/fmt/#Scan