# A program error **URL:** \ **Category:** Ruby\ **Created:** [December 16, 2009, 8:38am UTC](https://www.ruby-forum.com/t/a-program-error/180272 "2009-12-16T08:38:05Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![diabolator2](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b782af/32.png) [@diabolator2](https://www.ruby-forum.com/u/diabolator2)\ **Post date:** [December 16, 2009, 8:38am UTC](https://www.ruby-forum.com/t/a-program-error/180272/1 "2009-12-16T08:38:05Z")
hi, all! my compiler doesn’t like the “minus” in line 21, it’s like: /home/cristi/NetBeansProjects/RubyApplication3/lib/helic.rb:21: undefined method `-’ for “”:String (NoMethodError) 1 require “init.rb” 2 3 shots = 3 4 time = 1 5 speed = 0 6 x=y=1 7 while (shots!=0) do 8 #give entry data 9 puts “let’s f_ck da su\*\*er!" 10 puts “give speed:” 11 speed = gets 12 puts “give angle:” 13 angle = gets 14 #processing entry data 15 angle=(Math::PI)/180_angle.to\_f 16 xspeed=speed_Math.cos(angle) 17 yspeed=speed_Math.sin(angle) 18 #trajectory’s loop 19 while (y\>0) do 20 x=xspeed_time 21 y=yspeed_time-4.9\*time\*\*2 22 time+=0.01 23 24 #puts “x=”+x.to\_i.to\_s+” y="+y.to\_i.to\_s 25 screen.fill\_rect 0, 0, 640, 480, BGCOLOR 26 screen.draw\_circle x, y, 5, SHELLCOLOR 27 screen.flip 28 29 end 30 shots-=1 31 puts “shots remaining”+ shots.to\_s 32 end help, please. thanks! ---
**Author:** ![diabolator2](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b782af/32.png) [@diabolator2](https://www.ruby-forum.com/u/diabolator2)\ **Post date:** [December 16, 2009, 9:03am UTC](https://www.ruby-forum.com/t/a-program-error/180272/2 "2009-12-16T09:03:57Z")
it appears that yspeed is “”, which implies speed from gets is not what you expect it to be. puts speed after you gets it and see. ---
**Author:** ![diabolator2](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b782af/32.png) [@diabolator2](https://www.ruby-forum.com/u/diabolator2)\ **Post date:** [December 16, 2009, 9:19am UTC](https://www.ruby-forum.com/t/a-program-error/180272/3 "2009-12-16T09:19:45Z")
Zhao Lu wrote: > it appears that yspeed is “”, which implies speed from gets is not what > you expect it to be. puts speed after you gets it and see. The answer is speed = gets.to\_s puts speed gave integer, but puts xspeed(and yspeed too) gave “”. You were about right. I fell so stupid… Thanks! ---
**Author:** ![diabolator2](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b782af/32.png) [@diabolator2](https://www.ruby-forum.com/u/diabolator2)\ **Post date:** [December 16, 2009, 9:25am UTC](https://www.ruby-forum.com/t/a-program-error/180272/4 "2009-12-16T09:25:02Z")
> speed = gets.to\_s shit, I had to write speed = gets.to\_f sorry ---
**Author:** ![diabolator2](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b782af/32.png) [@diabolator2](https://www.ruby-forum.com/u/diabolator2)\ **Post date:** [December 16, 2009, 5:03pm UTC](https://www.ruby-forum.com/t/a-program-error/180272/5 "2009-12-16T17:03:52Z")
Hi, Am Mittwoch, 16. Dez 2009, 16:38:07 +0900 schrieb Teodor C.: > hi, all! my compiler doesn’t like the “minus” in line 21, it’s like: > > /home/cristi/NetBeansProjects/RubyApplication3/lib/helic.rb:21: > undefined method `-’ for “”:String (NoMethodError) > > […] > 20 x=xspeed_time > 21 y=yspeed_time-4.9\*time\*\*2 > […] Put something like this before line 21 and the cause of the error is obvious: puts [xspeed, yspeed, time].inspect Bertram ---
**Author:** ![diabolator2](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b782af/32.png) [@diabolator2](https://www.ruby-forum.com/u/diabolator2)\ **Post date:** [December 16, 2009, 9:39am UTC](https://www.ruby-forum.com/t/a-program-error/180272/6 "2009-12-16T09:39:03Z")
Try to use speed = gets.to\_i at line 11 and angle = gets.to\_i at line 13 to resolve this. Regards, Raghav