COMMAND$ function

Purpose: COMMAND$ returns the command line tail, that is, a character string containing everything typed on the command line after the filename that started the program.

 RetStr$ = COMMAND$

Example 1:

 DIM RetStr$
 RetStr$ = COMMAND$
 PRINT RetStr$

 RetStr$ = COMMAND$(ArgCount AS INTEGER)

Example 2:

 DIM cmd$
 DIM tailargs% = 0
   
 cmd$ = COMMAND$
   
 PRINT "Full command tail is: ", cmd$
 
 cmd$ = COMMAND$(tailargs%)
 
 PRINT "The executable name is ", cmd$
 
 DO
   tailargs++
   cmd$ = COMMAND$(tailargs%)
   IF cmd$ = NUL$ THEN
     tailargs--
     EXIT DO
   END IF
   PRINT "Argument", tailargs%, " is ", cmd$
 LOOP
  
 PRINT "Total command tail arguments:", tailargs%

Result: Compiling the above code to snip.exe and running with the command line

 snip one two three four five

the output is

 Full command tail is: one two three four five
 The executable name is snip
 Argument 1 is one
 Argument 2 is two
 Argument 3 is three
 Argument 4 is four
 Argument 5 is five
 Total command tail arguments: 5

Example 3: ARGC contains the number of arguments on the command line of the executed program.

 DIM cmd$
 DIM i%, tailargs%
    
 cmd$ = COMMAND$
 tailargs% = ARGC - 1
    
 PRINT "Full command tail: ", cmd$
 PRINT "The executable name is ", COMMAND$(0)
    
 FOR i% = 1 TO tailargs%
   cmd$ = COMMAND$(i)
   PRINT "Argument", i, " is ", cmd$
 NEXT i%
    
 PRINT "Total command tail arguments:", tailargs%

Result: Compiling the above code to snip.exe and running with the command line

 snip one two three four five

the output is

 Full command tail: one two three four five
 The executable name is snip
 Argument 1 is one
 Argument 2 is two
 Argument 3 is three
 Argument 4 is four
 Argument 5 is five
 Total command tail arguments: 5

Example 4:

 DIM i
 
 WHILE NOTNULL(COMMAND$(i))
   PRINT COMMAND$(i)
   INCR i
 WEND
 
 PAUSE

Result: Compiling the above code to My_Example.exe and running with the command line

 My_Example 000 111 222 333 444

the output is

 My_Example
 000
 111
 222
 333
 444

 Press any key to continue . . .

Remarks:
☞ Using COMMAND$ directly, as in this example

 IF COMMAND$(1) = "" OR COMMAND(2) = "" THEN
  PRINT "Usage: DoNotDoThis File1 File2"
  END
 END IF

can lead to undefined behavior. Sometimes it may work but, at other times, it will cause problems.

Always try to use an intermediate variable string to retrieve contents of COMMAND$, as in this example

 DIM RetStr1$
 DIM RetStr2$
 
 RetStr1$ = COMMAND$(1)
 RetStr2$ = COMMAND$(2)
 
 IF RetStr1$ = "" OR RetStr2$ = "" THEN
  PRINT "Usage: DoThis File1 File2"
  END
 END IF

Drag and Drop

COMMAND$ is drag and drop aware and can capture the path and name of a file that is drag and dropped or copied and pasted on to its executable.

The following example will show in a message box and print to a file the path\filename of any file dropped on it.

 DIM Filename$
 DIM A$
 
 Filename$ = APPEXEPATH$ & "TestFile.txt"
 
 OPEN Filename$ FOR APPEND AS FP1
 A$ = COMMAND$
 MSGBOX A$
 FPRINT FP1, A$
 CLOSE FP1

Launch Detection

When the following example is launched from the Windows File Explorer or similar file manager, the program detects that the launch was not from a command line console and displays an information message box containing the name of the executable with its directory location and a message that the application is command line only. When run from a command line console the message box is not displayed.

 IF CURSORX = 1 AND CURSORY = 1 AND COMMAND = "" THEN
  DIM TheMessage$, MsgRetVal%
 
  $FILL TheMessage$
  "This application, " & CRLF$
  APPEXENAME$ & CRLF$
  " is COMMAND LINE ONLY!" & CRLF$
  " It is located at " & CRLF$
  APPEXEPATH$ & APPEXENAME$ & CRLF$
  $FILL
 
  HIDE(CONWIN)
  MsgRetVal% = MSGBOX(TheMessage$, "COMMAND LINE ONLY!", MB_ICONASTERISK)
  END
 END IF
 
 PRINT "You DO know why you are looking at this !"

Remarks:
The above code is based on original source in the BCX translator which was written to display the BCX version and build info when the BCX executable is launched from the Windows File Explorer or similar file manager.

BCX Console Sample Programs using the COMMAND$ function.

S06.bas, S44.bas, S47.bas, S48.bas, S64.bas, S65.bas, S67.bas, S68.bas, S71.bas, S73.bas, S74.bas, S77.bas, S96.bas, S98.bas, S103.bas, S105.bas, S141.bas,

ARGC and ARGV$[] identifiers

Purpose: ARGC and ARGV$[] identifiers are case insensitive analogues to the C language parameters in the function

 INT main(INT argc, CHAR *argv[])

ARGC returns the full count of the command line, that is, the application invocation plus appended arguments. For example, the command line

 CommandCount one two three four five

calling a compilation of this "CommandCount.bas" BCX code

 PRINT ARGC

Result:

 6

The string array ARGV$[] contains each of the items on the command line. Entering the command line

 Commands one two three four five

calling a compilation of this "Commands.bas" BCX code

 FOR INTEGER OO = 0 TO ARGC - 1
   PRINT ARGV$[OO]
 NEXT

will output this

Result:

 Commands
 one
 two
 three
 four
 five

Remarks:
☞ ARGC and ARGV$[] are accessible only in Console mode and are scope limited to 'C' main. To access command line arguments from FUNCTION and SUB procedures and, as well, GUI mode programs, use the COMMAND$ function.

☞ ARGC and ARGV$[] are not available if coding using the BCX $NOMAIN directive with a user defined MAIN() function, such as,

  $NOMAIN
  
  SUB MAIN ()
   DIM RAW i
   i = 10
   PRINT i
  END SUB

the 'C' language main() function emitted by

  
 SUB MAIN ()

is

 INT main(void)

☞ If coding with the BCX $NOMAIN directive, with a user defined MAIN() function, and a parameterized

 INT main(INT argc, CHAR *argv[])

 $NOMAIN
   
 FUNCTION MAIN (ArgCount, ArgArray[] AS CHAR PTR)
   FOR INTEGER OO = 0 TO ArgCount - 1
     PRINT ArgArray$[OO]
   NEXT
 END FUNCTION

Compiling the above as NoMainArgs.bas and invoking with the command line

 NoMainArgs one two three four five

will output this

Result:

 NoMainArgs
 one
 two
 three
 four
 five

For INT main() details please see the ISO/IEC 9899 C Language Standard section 5.1.2.2.1 Program startup.

BCX Console Sample Programs using the ARGC and ARGV$[] functions.

s91.bas, s128.bas, s137.bas,