Problems with Read[stream,String] after Read[stream,Number]

*To*: mathgroup at smc.vnet.net*Subject*: [mg13776] Problems with Read[stream,String] after Read[stream,Number]*From*: "L. Dwynn Lafleur" <lafleur at usl.edu>*Date*: Mon, 24 Aug 1998 05:07:25 -0400*Organization*: University of Southwestern Louisiana*Sender*: owner-wri-mathgroup at wolfram.com

I have noticed what seems an inconsistency in the way Mathematica imports data from a file. The strange (to me, at least) behavior appears when one attempts to read a line with String data immediately after reading a line with Number data. In the following contrived notebook fragment, I expected that no more than four Read statements would be needed to import the four lines of data, one at a time, no matter whether they are interpreted as Strings or Numbers. (This is in Mathematica 3.0.1 under Windows 95.) --------------- In[2]:= !!test.dat 1 2 3 4 (***** Test 1 *****) In[3]:= strm=OpenRead["test.dat"]; In[4]:= Read[strm,String] (*Read Line 1 as String *) Out[4]= 1 In[5]:= Read[strm,Number] (*Read Line 2 as Number *) Out[5]= 2 In[6]:= Read[strm,String] (* Attempt to read Line 3 as String *) Out[6]= In[7]:= Read[strm,String] (* Second attempt to read Line 3 as String *) Out[7]= 3 In[8]:= Read[strm,Number] (* Read Line 4 as Number *) Out[8]= 4 In[9]:= Close[strm]; --------------- Note that the first attempt to read Line 3 fails. It is the only case of a String line being read after a Number line. A more thorough investigation shows that the extra Read line returns one of the characters (I have forgotten which) from the CR/LF line terminator used in DOS/Windows. Note there is no problem when a Number line is reaed after a String line. And the next test shows that String-after-String and Number-after-Number are okay. (***** Test 2 *****) In[10]:= strm=OpenRead["test.dat"]; In[11]:= Read[strm,String] (*Read Line 1 as String *) Out[11]= 1 In[12]:= Read[strm,String] (*Read Line 2 as String *) Out[12]= 2 In[13]:= Read[strm,Number] (*Read Line 3 as Number *) Out[13]= 3 In[14]:= Read[strm,Number] (* Read Line 4 as Number *) Out[14]= 4 In[15]:= Close[strm]; What am I missing here? A search of the Mathematica Bible, other books, and Deja News has only turned up examples of using Read and ReadList to import Strings followed by Numbers. That works the way I would have expected, as shown above. Thanks for any explanations or pointers thereto. -- L. Dwynn Lafleur Professor of Physics The University of Southwestern Louisiana Lafayette, Louisiana (USA) lafleur at usl.edu