[Help] any return flag/status from sqlplus?

If I issue a system call in a C program to call upon the sqlplus to update something by:

        int update_status;


	.

	.

        update_status = system("sqlplus username/password _at_input");


	.

	.

It seems that I cannot know from the value of update_status that there is any error or transaction failure. In my C program I have to know whether the update in sqlplus is successful or not in order to perform certain functions. Is there any way to do that? Your kind help will be much appreciated.

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NAME : Stephen NG Sze-ho    | Undergraduate, Year 3                           
EMAIL: cs_sng_at_ustsu4.ust.hk | Department of Computer Science                  
       cs_sng_at_ug.cs.ust.hk  | The Hong Kong University of Science & Technology