how to convert signed decimal to binary

i am converting signed decimal to binary reading value from file and after converting writing binary value in to file.here is my code but it gives me wrong answer

      % 
  fid = fopen('dec_bin.txt','r');
  fid1=fopen('dec_bin_con.txt','w');
  tline = fgetl(fid);
  while ischar(tline)
      disp(tline);
      abstline=abs(tline);

      if abstline==tline
      out_1a=dec2bin(tline,8);
      else
       out_1a=dec2bin(tline+256,8); 
      end;
       disp(out_1a);
       fprintf(fid1,'%s \n',out_1a);
       fprintf(fid1,'\n');

      tline = fgetl(fid);
  end
  fclose(fid);
  fclose(fid1);

this is my dec_bin file:

0
-1
1
-2
2
-3
3
-4
4

and my output is:

00110000 

0000110110100011 

00110001 

0000110110100110 

00110010 

0000110110100111 

00110011 

0000110110110010 

00110100

Answer 1

[Walter Roberson]

fgetl() returns a string. You are doing conversion on the characters . If you want to do conversion on the values represented by those characters, you need to convert the strings to numeric form, such as with str2double()

[saurabh shukla]

thank you ,now i am getting right output.