Creating a Simple Program

In this section, we'll create a simple "Hello World" program consisting of two .pro files. Start the IDL Workbench and complete the steps described below.

Note
For information on using the IDL Editor, see

  1. Open a new IDL Source File. Start the IDL Editor by selecting File → IDL Source File or clicking the New IDL Source File button on the toolbar.
  2. Create a procedure. Type the following in the IDL Editor:
    3. PRO hello_main 
   name = '' 
   READ, name, PROMPT='Enter Name: ' 
   str = HELLO_WHO(name) 
   PRINT, str 
END
  3. Save the procedure. To save the file, select File → Save or click the Save button on the toolbar. Save the file with the name hello_main.pro in the main IDL directory (which the Save As dialog should already show).
  4. Create a function. Open a new IDL source file by selecting File → IDL Source File or clicking the New IDL Source File button on the toolbar. Enter the following code:
    5. FUNCTION hello_who, who 
   RETURN, 'Hello ' + who 
END
  5. Save the function. Save the file as hello_who.pro in the main IDL directory. This simple program, consisting of a user-defined procedure, calls a user-defined function.
  6. Compile the programs. Compile hello_main.pro and hello_who.pro programs by selecting Project → Build All.

    7. Note
    You can also type .COMPILE hello_who.pro, hello_main.pro at the IDL command prompt to compile the files. With functions, the compilation order does matter. See Compiling Your Program for details.

  7. Run the program. Select Run → Run hello_main.
  8. Enter a name. Type your name at the IDL command line, which now reads "Enter Name" and press the Enter key. This passes the text to the function hello_who. The "Hello name" string is returned to the procedure and printed in the Console View.