3

I need your opinion of what is going wrong.

From home I wrote a program using Bloodsheed and got the wanted result. The purpose of the programm is to display lines from a source file to output a text with a certain width. The source file can not be analysed line by line. Instead it should be read using char and string word.

Then I went to uni to submit my program using TextPad and Borland: the output is different: spaces between words and some end of line characters are ignored. I do not understand what is going on. I have spent the all day on the case unsuccessfully. Do compiler use differently the operator >> to read string? It looks like in the first case it stops before the space or end of line character in the second one it discard them. Have you got a suggestion about the problem?

At home the successful output is:

Max line length: 40

___Inglis_(1994)_describes_it_thus:

"For_output_of___floating-point_numbers,
the_format_strings_used_by_printf_may
include_%f_or_%e_(or_%g,_which_we_will
ignore).__These_have_much_in_common_with
%i:

____"A_minus_sign_indicates_left
justification,_a_plus_sign_indicates
that_the_converted_value_will_start_with
a_plus_sign_if_it_is_positive,_and_a
minimum_field_width_and/or_a_precision
may_be_specified.

At uni:

Max line length: 40

___Inglis(1994)describesitthus:

"Foroutputof__floating-pointnumbers,the
formatstringsusedbyprintfmayinclude%for
%e(or%g,whichwewillignore)._Thesehave
muchincommonwith%i:
____"Aminussignindicatesleft
justification,aplussignindicatesthatthe
convertedvaluewillstartwithaplussignifit
ispositive,andaminimumfieldwidthand/ora
precisionmaybespecified.

function which is going wrong:

void Text::display(ofstream & out)
{ ifstream from(infileName.c_str());
  if (from.fail())
  { cerr<<infileName<<" not open\n";
    exit(1);
  }
  out<<"Max line length: "<<lineLength<<endl<<endl;
  string s, w;   //s stands for space, w for word
  char l;        //l stands for letter
  int c=0;       //c syands for count
  while(true)
  { if(static_cast<int>(w.length())>0)
    {  if(lineLength<w.length())
       { cerr <<"The line length "<<lineLength
             <<" is not long enough.\n"<<"The longuest word is "
             <<w<<" and has "<<w.length()
             <<" letters.\n";
         exit(1);
       }
       c+=w.length();
       out<<w;
       w.erase();
    }
    from.get(l);
    if (from.fail())
    {  out<<endl;
       break;
    }
    if (l=='\n')
    {  out<<l;
       s.erase();
       c=0;
       continue;
    }
    while (l==' ')
    {  s.push_back('_');
       c++;
       from.get(l);
    }
    if (l=='\n')
    {  out<<l;
       s.erase();
       c=0;
       continue;
    }
    from.putback(l);
    from>>w;
    c+=w.length();
    if (lineLength<c)
    {  out<<endl;
       s.erase();
       c=0;
    }
    else if(w.length()>0)
    {  out<<s<<w;
       w.erase();
       s.erase();
    }
  }
}
4

1 回答 1

7

这是不同换行表示的症状。

在“家”，您的换行符是 LF（'\n'或0x0A）。

在“uni”处，您的换行符是 CR+LF（'\r\n'或0x0D0A）。

您的代码仅允许 LF 换行符。

作为旁白...

string s, w;   //s stands for space, w for word
char l;        //l stands for letter
int c=0;       //c syands for count

C++ 允许标识符长于单个字符。以下内容更具表现力，无需注释，并使您的代码维护更加容易。

std::string space, word;
char letter;
int count = 0;
于 2011-12-16T23:36:31.330 回答