'Returning "String" value from Console Application to Batch File

Currently, my console application can return Integer values from the console application via the kernel32 function ExitProcess.

Public Declare Sub ExitProcess Lib "kernel32" (ByVal uExitCode As Long)

How do I return string values from the console application to the batch file?

I want to return string values like Successfully transformed 100 batches... etc.

vb6vb6-migration


Solution 1:[1]

On most platforms (and also in Windows) process exit codes are integer values, but you could write string data to the standard output stream by using the GetStdHandle and WriteFile functions.

Update As requested, I´ll serve you an example.

First, you´ll need to import some more Windows functions and define the required constants. In addition to the before-mentioned GetStdHandle and WriteFile methods, the AttachConsole and FreeConsole methods are also required.

Private Const ATTACH_PARENT_PROCESS As Long = -1

Private Declare Function AttachConsole Lib "Kernel32" ( _
    ByVal dwProcessId As Long) As Long

Private Declare Function FreeConsole Lib "Kernel32" () As Long

Private Const STD_OUTPUT_HANDLE As Long = -11&

Private Declare Function GetStdHandle Lib "Kernel32" ( _
    ByVal nStdHandle As Long) As Long

Private Declare Function WriteFile Lib "Kernel32" ( _
    ByVal hFile As Long, _
    ByVal lpBuffer As String, _
    ByVal nNumberOfBytesToWrite As Long, _
    ByRef lpNumberOfBytesWritten As Long, _
    lpOverlapped As Any) As Long

In my sample project, I just added a Module and defined a Sub Main method - this serves as the entry point for the app. Please notice, that you don´t get any output from the app when running it from the VB6 IDE debugger. You´ll need to compile it, and run it from a terminal window (for instance cmd.exe).

The first thing to do is to attach to the console of the parent process (which is the console of the terminal window). Otherwise, the GetStdHandle method will return zero.

Dim handle As Long
AttachConsole (ATTACH_PARENT_PROCESS)
handle = GetStdHandle(STD_OUTPUT_HANDLE)

Once the console handle is obtained, the WriteFile method can be used to print text to the console.

Dim s As String
Dim numberOfBytesWritten As Long
    
s = "Hello World."
WriteFile handle, s, Len(s), numberOfBytesWritten, ByVal 0&

Before finally calling ExitProcess, the FreeConsole method is used to detach the process from the parent console.

Sources

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Source: Stack Overflow

Solution Source
Solution 1

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