How To Redirect Standard I/O of a Console App Using Batch File

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Step-by-Step Example

1. Create a console application, CONSOL.EXE, that expects an integer as its STDIN and sends a text string out as its STDOUT, using the following C code:

         #include <stdio.h>
   
         void main(void)
         {
               int i;
               scanf("%d", &i);
               printf("\nSTDIn is %d!\n", i);
         }
   
   						

2. Create a batch file, named REDIRECT.BAT, that contains only the following command line:
   
   type stdin.txt | consol.exe > stdout.txt
3. Create a new text file using Notepad or any text editor. Enter an integer and press the ENTER key. Save the file as "stdin.txt."
4. Start a new project in Visual Basic. Form1 is created by default.
5. Add the following code to the General Declarations section of Form1:

         Private Declare Function OpenProcess Lib "kernel32.dll" (ByVal _
            dwAccess As Long, ByVal fInherit As Integer, ByVal hObject _
            As Long) As Long
   
         Private Declare Function CloseHandle Lib "kernel32" (ByVal _
            hObject As Long) As Long
   
         Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal _
          hHandle As Long, ByVal dwMilliseconds As Long) As Long
   
         Const SYNCHRONIZE = &H100000
         Const NORMAL_PRIORITY_CLASS = &H20&
         Const INFINITE = -1&
   
   						

6. Add the following code to the Form1_Click event:

         ProcessID& = Shell("test.bat", vbNormalFocus)
         ProcessHandle& = OpenProcess(SYNCHRONIZE, True, ProcessID&)
         WaitForSingleObject ProcessHandle&, -1&
         CloseHandle ProcessHandle&
   
   						

7. Save Form1 and Project1 to the same directory as REDIRECT.BAT and CONSOL.EXE. Press the F5 key to run the program. Click Form1. A console window is displayed briefly and closes itself. The STDOUT.TXT file is then created in the same directory.