Simple managed app won't work...

[billr]

Excuse me if you consider this a cross post, however, it was originally destined for this group not the vc.atl group, but somehow it went there instead of here! (obviously it was something I did, but hey ho) ... now back to the problem in hand

I've made what I consider to be the simplest of applications, but it won't work. This is my code

#using <mscorlib.dll>
#include <tchar.h>
using namespace System;

int _tmain(void)
{
String* args[] = Environment::GetCommandLineArgs();

try
{
try
{
Console::WriteLine(String::Format(S"You supplied {0} arguments", __box(args->Length)));
}
catch(Exception* e)
{
Console::WriteLine(S"\nERROR WITH args\n---------------\n");
Console::WriteLine(e->Message);
Console::WriteLine(e->TargetSite);
Console::WriteLine(e->StackTrace);
}

if(!args)
Console::WriteLine(S"\nYou didn't supply any arguments\nVielleicht das nachster zeit!\n\n");
else if(args->Length > 1)
Console::WriteLine(S"\nYou supplied too many arguments\nVielleicht das nachster zeit!\n\n");
else
{
int counter = Int32::Parse(args[0]);
for(int i = 0; i < counter; i++)
{
Console::WriteLine(S"I am a programmer.");
}
Console::WriteLine(S"");
}
}
catch(Exception* e)
{
Console::WriteLine(S"\nERROR\n-----\n");
Console::WriteLine(e->Message);
Console::WriteLine(e->TargetSite);
Console::WriteLine(e->StackTrace);
}

return 0;
}

and this is the result of running the application:

W:\C++\MTest\Debug>MTest

ERROR WITH args
---------------

Object reference not set to an instance of an object.
Int32 main()
at main() in w:\c++\mtest\mtest.cpp:line 20

ERROR
-----

Input string was not in a correct format.
Int32 ParseInt32(System.String, System.Globalization.NumberStyles, System.Globalization.Nu
mberFormatInfo)
at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
at System.Int32.Parse(String s)
at main() in w:\c++\mtest\mtest.cpp:line 36

W:\C++\MTest\Debug>MTest 2

ERROR WITH args
---------------

Object reference not set to an instance of an object.
Int32 main()
at main() in w:\c++\mtest\mtest.cpp:line 20

You supplied too many arguments
Vielleicht das nachster zeit!

[martink]

Looks like you want an app that takes a single command-line argument (eg. 'mtest 3'), and it specifying the number of times 'I am a programmer.' is displayed.

args->length is the number of command-line parts - of which there is at least 1, the full path to the app itself (eg. 'c:\test\mtest.exe'). So change it your code to;

if(args->length < 2)
Console::WriteLine(S"\nYou didn't supply any arguments\nVielleicht das nachster zeit!\n\n");
else if(args->Length > 2)
Console::WriteLine(S"\nYou supplied too many arguments\nVielleicht das nachster zeit!\n\n");
else
{
int counter = Int32::Parse(args[1]);
for(int i = 0; i < counter; i++)
{
Console::WriteLine(S"I am a programmer.");
}
Console::WriteLine(S"");
}

"billr" wrote:

Excuse me if you consider this a cross post, however, it was originally destined for this group not the vc.atl group, but somehow it went there instead of here! (obviously it was something I did, but hey ho) ... now back to the problem in hand

I've made what I consider to be the simplest of applications, but it won't work. This is my code

#using <mscorlib.dll>
#include <tchar.h>
using namespace System;

int _tmain(void)
{
String* args[] = Environment::GetCommandLineArgs();

try
{
try
{
Console::WriteLine(String::Format(S"You supplied {0} arguments", __box(args->Length)));
}
catch(Exception* e)
{
Console::WriteLine(S"\nERROR WITH args\n---------------\n");
Console::WriteLine(e->Message);
Console::WriteLine(e->TargetSite);
Console::WriteLine(e->StackTrace);
}

if(!args)
Console::WriteLine(S"\nYou didn't supply any arguments\nVielleicht das nachster zeit!\n\n");
else if(args->Length > 1)
Console::WriteLine(S"\nYou supplied too many arguments\nVielleicht das nachster zeit!\n\n");
else
{
int counter = Int32::Parse(args[0]);
for(int i = 0; i < counter; i++)
{
Console::WriteLine(S"I am a programmer.");
}
Console::WriteLine(S"");
}
}
catch(Exception* e)
{
Console::WriteLine(S"\nERROR\n-----\n");
Console::WriteLine(e->Message);
Console::WriteLine(e->TargetSite);
Console::WriteLine(e->StackTrace);
}

return 0;
}

and this is the result of running the application:

W:\C++\MTest\Debug>MTest

ERROR WITH args
---------------

Object reference not set to an instance of an object.
Int32 main()
at main() in w:\c++\mtest\mtest.cpp:line 20

ERROR
-----

Input string was not in a correct format.
Int32 ParseInt32(System.String, System.Globalization.NumberStyles, System.Globalization.Nu
mberFormatInfo)
at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
at System.Int32.Parse(String s)
at main() in w:\c++\mtest\mtest.cpp:line 36

W:\C++\MTest\Debug>MTest 2

ERROR WITH args
---------------

Object reference not set to an instance of an object.
Int32 main()
at main() in w:\c++\mtest\mtest.cpp:line 20

You supplied too many arguments
Vielleicht das nachster zeit!

[billr]

"martink" wrote:

Looks like you want an app that takes a single command-line argument (eg. 'mtest 3'), and it specifying the number of times 'I am a programmer.' is displayed.

args->length is the number of command-line parts - of which there is at least 1, the full path to the app itself (eg. 'c:\test\mtest.exe'). So change it your code to;
that makes sense, however, this is the line throwing the first Exception
Console::WriteLine(String::Format(S"You supplied {0} arguments", __box(args->Length)));
and the Exception message is
Object reference not set to an instance of an object.

This Exception is thrown whether or not any command line args are supplied

[billr]

Thank you martink, with your help I seem to have found the problem, though a little more reading is obviously required with regards to property accessors.

First off, I must adjust my array checking accordingly, to take into account the fact that the first command-line arg is the full path to the app.

Next, instead of simpy using the args->Length property I have changed the code to call the C++ accessor function. i.e. args->get_Length(), and this works a treat.

thus the fresh code looks like this ....

try
{
int len = args->get_Length() - 1;

try
{
Console::WriteLine(String::Format(S"You supplied {0} arguments", __box(len)));
}
catch(Exception* e)
{
Console::WriteLine(S"\nERROR WITH args\n---------------\n");
Console::WriteLine(e->Message);
Console::WriteLine(e->TargetSite);
Console::WriteLine(e->StackTrace);
}

if(len == 0)
Console::WriteLine(S"\nYou didn't supply any arguments\nVielleicht das nachster zeit!\n\n");
else if(len > 1)
Console::WriteLine(S"\nYou supplied too many arguments\nVielleicht das nachster zeit!\n\n");
else
{
int counter = Int32::Parse(args[1]);
for(int i = 0; i < counter; i++)
{
Console::WriteLine(String::Format(S"{0}: I am a programmer.", __box(i+1)));
}
Console::WriteLine(S"");
}
}
catch(Exception* e)
{
Console::WriteLine(S"\nERROR\n-----\n");
Console::WriteLine(e->Message);
Console::WriteLine(e->TargetSite);
Console::WriteLine(e->StackTrace);
}