如何编码空间去除

Question

这里时，我摆脱过去的空间我艾菲尔代码为我的空间去除分配：

feature {NONE} -- Main routine 
copy_file 
-- Copy a file character by character from input to output 
require 

input_open: input.is_readable 
output_open: output.is_writable 
local flag: INTEGER 

do 
flag := 0  -- 0 for previous space, 1 for previous char 
from read_char -- Must prime the pump by reading the first character 
until ch = EOF 
loop 
    from 
     ch := input.last_character 
    until 
     ch = EOL 
    loop 
     if ch = Space_char and flag = 0 then  -- leading spaces 
      read_char 
     elseif ch /= Space_char and flag = 0 then -- see first charater after space 
      output.putchar (ch) 
      flag := 1 
      read_char 
     elseif ch = Space_char and flag = 1 then -- see space after characters 
      output.putchar (Space_char) 
      flag := 0 
      read_char 
     elseif ch /= Space_char and flag = 1 then -- see character after character 
      output.putchar (ch) 
      read_char 
     end 
    end 
    flag := 0 
    read_char 
end 

    -- At end of file, nothing to do in Eiffel except close the files 
input.close 
output.close 
end 

这里是样本输入：

  Leading spaces 
Training spaces      
    Leading and trailing spaces      
Only interword  spaces 
    Leading, trailing  and  interword  spaces   
This line has correct spaces 

Previous line was empty 

Previous line has only leader spaces 
OneWordLine 
Three word line 

我跑代码和我得到的输出是略有不同的要求，比如说，当线中有一个尾部空格时，我总是会得到一个额外的空间。

这里是我的输出：

Leading spaces 
Training spaces 
Leading and trailing spaces 
Only interword spaces 
Leading, trailing and interword spaces 
This line has correct spaces 

Previous line was empty 

Previous line has only leader spaces 
OneWordLine 
Three word line 

有人可以帮我吗？

Answer 1

当您读取第一个空格字符时，请勿立即打印。等待下一个非空格字符将其打印出来，如果您收到EOL字符，则不会打印它。这里是你的算法修改：

feature {NONE} -- Main routine 
copy_file 
-- Copy a file character by character from input to output 
require 

input_open: input.is_readable 
output_open: output.is_writable 
local flag: INTEGER 

do 
flag := 0  -- 0 for previous space, 1 for previous char 
from read_char -- Must prime the pump by reading the first character 
until ch = EOF 
loop 
    has_read_space := False 
    from 
     ch := input.last_character 
    until 
     ch = EOL 
    loop 
     if ch = Space_char and flag = 0 then  -- leading spaces 
      read_char 
     elseif ch /= Space_char and flag = 0 then -- see first charater after space 
      if has_read_space then 
       output.putchar (Space_char) -- Print the space when reading a character 
       has_read_space := False 
      end 
      output.putchar (ch) 
      flag := 1 
      read_char 
     elseif ch = Space_char and flag = 1 then -- see space after characters 
      has_read_space := True -- Don't print it right now 
      flag := 0 
      read_char 
     elseif ch /= Space_char and flag = 1 then -- see character after character 
      output.putchar (ch) 
      read_char 
     end 
    end 
    flag := 0 
    read_char 
end 

    -- At end of file, nothing to do in Eiffel except close the files 
input.close 
output.close 
end