# MATLAB: Searching a given line in a text file

text file

The following file is a txt file in sdf format(chemical structures) It looks sumthin lik this
   7  9  1  0  0  0  0    7 14  1  0  0  0  0    8 10  1  0  0  0  0    8 15  1  0  0  0  0    9 10  2  0  0  0  0    9 16  1  0  0  0  0   10 17  1  0  0  0  0   12 13  1  0  0  0  0   13 18  1  0  0  0  0   13 19  1  0  0  0  0   13 20  1  0  0  0  0  M  END  > <PUBCHEM_COMPOUND_CID>  2244> <PUBCHEM_COMPOUND_CANONICALIZED>1> <PUBCHEM_CACTVS_COMPLEXITY>212I need to extract just the information under the CID number field and there could be multiple CID number fields in a single file.. How should I go about this?? Any help would be appreciated..

#### Best Answer

• I tried sumthin lik this
[A,B]=uigetfile('*.sdf','sdf');C=fopen(A,'r');n=0;i=<ui>;  %number of structures -- wil be obtained from the userpubchem_id=[];z=<ui>*300; %rough approximation-- 300lines for each structurefor j=1:1:zD=fgetl(C);if strcmp('> <PUBCHEM_COMPOUND_CID>',D)E=fgetl(C); E = str2double(E);pubchem_id=[pubchem_id; E]endend
and it worked :)