Now to keep our promise about the exit(4) statement. Redisplay the file named special.c on your monitor. The last statement simply exits the program and returns the value of 4 to MS-DOS. Any number from 0 to 9 can be used in the parentheses for DOS communication. If you are operating in a BATCH file, this number can be tested with the "ERRORLEVEL" command. Note that these characteristics only apply to MS-DOS. Most compilers that operate in several passes return a 1 with this mechanism to indicate that a fatal error has occurred and it would be a waste of time to go on to another pass resulting in even more errors.
It is therefore wise to use a batch file for compiling programs and testing the returned value for
errors.
It is therefore wise to use a batch file for compiling programs and testing the returned value for
errors.
