In Ruby, how can I print my next prompt on the same line after user input?

Question

I'm tinkering with a basic Tower of Hanoi game, and trying to get user input twice, but print both prompts on the same line (separated by the first input). I've searched for awhile, maybe I'm using the wrong terms. I assume the new line is due to gets, or setting it to a variable, but how do I get rid of it? Thanks!

print "Move FROM which tower? (1 / 2 / 3) "
answer1 = gets.chomp.to_i
print "...TO which tower? (1 / 2 / 3) "
answer2 = gets.chomp.to_i

I want this:

Move FROM which tower? (1 / 2 / 3) 1 ...TO which tower? (1 / 2 / 3) 2

But I'm getting this:

*Move FROM which tower? (1 / 2 / 3) 1

...TO which tower? (1 / 2 / 3) 2

(input in bold)

See http://stackoverflow.com/questions/174933/how-to-get-a-single-character-without-pressing-enter — Linuxios, Feb 24 '15 at 19:28

score 3 · Accepted Answer · answered Feb 24 '15 at 19:41

The reason you get a new line even after chomp is because in the terminal you've already entered the carriage return key which displays the new line.

What you want can be done like this:

require "io/console"
print "Move FROM which tower? (1 / 2 / 3) "
x = STDIN.getch.to_i
print x
print "...TO which tower? (1 / 2 / 3) "
y = STDIN.getch.to_i
print "#{y}\n"
print "Result: (#{x}, #{y})"

Note this will give an output of this:

$ ruby tower.rb
Move FROM which tower? (1 / 2 / 3) 1...TO which tower? (1 / 2 / 3) 2
Result: (1, 2)

Note this only gets one character from STDIN.

score 1 · Answer 2 · answered Feb 24 '15 at 19:41

1

In windows this does the thing

require "Win32API"

def read_char
  Win32API.new("crtdll", "_getch", [], "L").Call
end

print "Move FROM which tower? (1 / 2 / 3) "
print answer1 = read_char.chr
print "...TO which tower? (1 / 2 / 3) "
puts answer2 = read_char.chr

puts answer1+answer2

gives

#Move FROM which tower? (1 / 2 / 3) 1...TO which tower? (1 / 2 / 3) 2
#12

answered Feb 24 '15 at 19:41

peter

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If Leo's answer works in Linux, it is better because it works in windows also – peter Feb 24 '15 at 19:43

score 1 · Answer 3 · answered Feb 24 '15 at 20:05

Here is some other tricks using ANSI escape sequences

print "From Number "
num1 = gets.chomp.to_i
print "\033[1A\033[14C...TO Number "
num2 = gets.chomp.to_i

output

[arup@Ruby]$ ruby a.rb
From Number 1  ...TO Number 2
[arup@Ruby]$

Move the cursor up N lines: \033[NA
Move the cursor forward N columns: \033[NC

Values of N you must need to be calculated as per the need. Cursor Movement.

In Ruby, how can I print my next prompt on the same line after user input?

3 Answers3