How do I save structured objects into mat-files?

I am dealing with large object in my research. I am not familiar with class oriented programing in MATLAB. However, I wanted to save the object into Mat-files. I tried two following ways. But neither way works out with separate message:

objMain.obj1 = function1(Variables);
objMain.obj2 = function1(Variables);
objMain.obj3 = function1(Variables);
objMain.obj4 = function1(Variables);
dir2Save  = 'C:\Documents\Matlab\Research';
fname  = ['mainTask' int2str(1)];
save([dir2Save '\' fname '.mat'], objMain);

    *Message:* _Error using save
    _Argument must contain a string._

save([dir2Save '\' fname '.mat'], '-struct', objMain);

    *Message:* _Error using save
    The argument to -STRUCT must be the name of a scalar structure variable._

Does any body have any ideas how to solve....

Thanks for your help.

Mahesh

[Stephen23]

@Mahesh: I fixed your incorrect terminology: an M-file is a script or function, a mat file is a binary file used to store data.

Answer 1

[the cyclist]

Try

save([dir2Save '\' fname '.mat'], 'objMain')

You needed to enclose the variable name in quotes, as the second argument.

[Walter Roberson]

save( fullfile(dir2Save, [fname '.mat']), 'objMain')

[Mahesh]

Thank you so much...

[Stephen23]

@Mahesh: it is better to use fullfile than a simple concatenation.

[the cyclist]

Cross-platform compatibility, or other reasons?

[Mahesh]

I am not sure about fullfile. Could you please help me how to use such. Since I am making file name as variable depending upon the parameters. Thanks for suggestions