A program error

Ruby
1

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 fck 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)/180angle.to_f
16 xspeed=speedMath.cos(angle)
17 yspeed=speedMath.sin(angle)
18 #trajectory’s loop
19 while (y>0) do
20 x=xspeedtime
21 y=yspeedtime-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!

2

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.

3

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!

4

speed = gets.to_s

shit, I had to write

speed = gets.to_f

sorry

5

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=xspeedtime
21 y=yspeedtime-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

6

Try to use
speed = gets.to_i at line 11 and
angle = gets.to_i at line 13 to resolve this.

Regards,
Raghav