Identify a line in a file that contains a specific string

%识别文件中的这一行：' cell  2                                                                                                               ' :
func('o100.txt','reco400.txt','cell  2');

function linenum=func(filein,fileout,line)
fidin=fopen(filein, 'r');
fidout=fopen(fileout, 'w');
nline= 0;
while ~feof(fidin) % 判断是否为文件末尾
    tline = fgetl(fidin); % 从文件读行
    nline = nline + 1;
     if contains(tline, line)
        fprintf(fidout, '%s\n',num2str(nline));
        fprintf(fidout, '%s\n',tline);
        linenum = nline; %行数作为输出
    end
end
fclose(fidin);
fclose(fidout);
end