What is the Delphi equivalent for LPLONG?

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I have to access several functions of a DLL written in c from Delphi (currently Delphi7).
I can do it without problems when the parameters are scalar
(thanks to the examples found in this great site!), but I have been stuck for some time when in the parameters there is a pointer to an array of Longs.

This is the definition in the header file of one of the functions:

BOOL __stdcall BdcValida (HANDLE h, LPLONG opcl);

(opcl is an array of longs)

And this is a portion of my Delphi code:

type

  TListaOpciones= array of LongInt; //I tried with static array too! 

  Popcion = ^LongInt; //tried with integer, Cardinal, word...  

var

  dllFunction: function(h:tHandle;  opciones:Popcion):boolean;stdcall;

  arrayOPciones:TListaOpciones;

  resultado:boolean;

begin

  .....

  I give values to aHandle and array arrayOPciones

  .....

  resultado:=dllFunction(aHandle, @arrayopciones[0]);

end;

The error message when executing it is:

"Project xxx raised too many consecutive exceptions: access violation
at 0x000 .."

What is the equivalent in Delhpi for LPLONG? Or am I calling the function in an incorrect way?
Thank you!

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

I must admit that I find the function call confusing, in that if opcl really is a pointer to an array, and not, say, a single variable, I don't see how the DLL knows how big that array is - that is to say there is no parameter telling it unless it is stored in whatever h is pointing to.

– Dsm
Jan 3 at 13:53

The DLL knows the size of the array, it varies depending on the context and we know it through functions of the dll that inform it.

– Martín Castro Aguirrezabala
Jan 3 at 14:02

You are saying there is a different function to set the array length for the DLL. Are you sure that you are setting it correctly? Maybe you are passing a value that is too high (probably by one).

– dummzeuch
Jan 3 at 14:16

Relevant bits of the code are missing to understand who and where the memory is allocated and freed and how the size of the array is passed.

– Remko
Jan 4 at 10:08

add a comment |

This is the definition in the header file of one of the functions:

BOOL __stdcall BdcValida (HANDLE h, LPLONG opcl);

(opcl is an array of longs)

And this is a portion of my Delphi code:

type

  TListaOpciones= array of LongInt; //I tried with static array too! 

  Popcion = ^LongInt; //tried with integer, Cardinal, word...  

var

  dllFunction: function(h:tHandle;  opciones:Popcion):boolean;stdcall;

  arrayOPciones:TListaOpciones;

  resultado:boolean;

begin

  .....

  I give values to aHandle and array arrayOPciones

  .....

  resultado:=dllFunction(aHandle, @arrayopciones[0]);

end;

The error message when executing it is:

"Project xxx raised too many consecutive exceptions: access violation
at 0x000 .."

What is the equivalent in Delhpi for LPLONG? Or am I calling the function in an incorrect way?
Thank you!

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

I must admit that I find the function call confusing, in that if opcl really is a pointer to an array, and not, say, a single variable, I don't see how the DLL knows how big that array is - that is to say there is no parameter telling it unless it is stored in whatever h is pointing to.

– Dsm
Jan 3 at 13:53

The DLL knows the size of the array, it varies depending on the context and we know it through functions of the dll that inform it.

– Martín Castro Aguirrezabala
Jan 3 at 14:02

You are saying there is a different function to set the array length for the DLL. Are you sure that you are setting it correctly? Maybe you are passing a value that is too high (probably by one).

– dummzeuch
Jan 3 at 14:16

Relevant bits of the code are missing to understand who and where the memory is allocated and freed and how the size of the array is passed.

– Remko
Jan 4 at 10:08

add a comment |

This is the definition in the header file of one of the functions:

BOOL __stdcall BdcValida (HANDLE h, LPLONG opcl);

(opcl is an array of longs)

And this is a portion of my Delphi code:

type

  TListaOpciones= array of LongInt; //I tried with static array too! 

  Popcion = ^LongInt; //tried with integer, Cardinal, word...  

var

  dllFunction: function(h:tHandle;  opciones:Popcion):boolean;stdcall;

  arrayOPciones:TListaOpciones;

  resultado:boolean;

begin

  .....

  I give values to aHandle and array arrayOPciones

  .....

  resultado:=dllFunction(aHandle, @arrayopciones[0]);

end;

The error message when executing it is:

"Project xxx raised too many consecutive exceptions: access violation
at 0x000 .."

What is the equivalent in Delhpi for LPLONG? Or am I calling the function in an incorrect way?
Thank you!

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

This is the definition in the header file of one of the functions:

BOOL __stdcall BdcValida (HANDLE h, LPLONG opcl);

(opcl is an array of longs)

And this is a portion of my Delphi code:

type

  TListaOpciones= array of LongInt; //I tried with static array too! 

  Popcion = ^LongInt; //tried with integer, Cardinal, word...  

var

  dllFunction: function(h:tHandle;  opciones:Popcion):boolean;stdcall;

  arrayOPciones:TListaOpciones;

  resultado:boolean;

begin

  .....

  I give values to aHandle and array arrayOPciones

  .....

  resultado:=dllFunction(aHandle, @arrayopciones[0]);

end;

The error message when executing it is:

"Project xxx raised too many consecutive exceptions: access violation
at 0x000 .."

What is the equivalent in Delhpi for LPLONG? Or am I calling the function in an incorrect way?
Thank you!

delphi dll interop

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

asked Jan 3 at 13:36

Martín Castro Aguirrezabala

112

I must admit that I find the function call confusing, in that if opcl really is a pointer to an array, and not, say, a single variable, I don't see how the DLL knows how big that array is - that is to say there is no parameter telling it unless it is stored in whatever h is pointing to.

– Dsm
Jan 3 at 13:53

The DLL knows the size of the array, it varies depending on the context and we know it through functions of the dll that inform it.

– Martín Castro Aguirrezabala
Jan 3 at 14:02

You are saying there is a different function to set the array length for the DLL. Are you sure that you are setting it correctly? Maybe you are passing a value that is too high (probably by one).

– dummzeuch
Jan 3 at 14:16

Relevant bits of the code are missing to understand who and where the memory is allocated and freed and how the size of the array is passed.

– Remko
Jan 4 at 10:08

add a comment |

I must admit that I find the function call confusing, in that if opcl really is a pointer to an array, and not, say, a single variable, I don't see how the DLL knows how big that array is - that is to say there is no parameter telling it unless it is stored in whatever h is pointing to.

– Dsm
Jan 3 at 13:53

The DLL knows the size of the array, it varies depending on the context and we know it through functions of the dll that inform it.

– Martín Castro Aguirrezabala
Jan 3 at 14:02

You are saying there is a different function to set the array length for the DLL. Are you sure that you are setting it correctly? Maybe you are passing a value that is too high (probably by one).

– dummzeuch
Jan 3 at 14:16

Relevant bits of the code are missing to understand who and where the memory is allocated and freed and how the size of the array is passed.

– Remko
Jan 4 at 10:08

I must admit that I find the function call confusing, in that if opcl really is a pointer to an array, and not, say, a single variable, I don't see how the DLL knows how big that array is - that is to say there is no parameter telling it unless it is stored in whatever h is pointing to.

– Dsm
Jan 3 at 13:53

The DLL knows the size of the array, it varies depending on the context and we know it through functions of the dll that inform it.

– Martín Castro Aguirrezabala
Jan 3 at 14:02

You are saying there is a different function to set the array length for the DLL. Are you sure that you are setting it correctly? Maybe you are passing a value that is too high (probably by one).

– dummzeuch
Jan 3 at 14:16

Relevant bits of the code are missing to understand who and where the memory is allocated and freed and how the size of the array is passed.

– Remko
Jan 4 at 10:08

add a comment |

1 Answer
1

active

oldest

votes

LONG maps to Longint, and LPLONG maps to ^Longint. So, you have translated that type correctly.

You have translated BOOL incorrectly though. It should be BOOL or LongBool in Delphi. You can use either, the former is an alias for the latter.

Your error lies in code or detail we can't see. Perhaps you didn't allocate an array. Perhaps the array is incorrectly sized. Perhaps the handle is not valid. Perhaps earlier calls to the DLL failed to check for errors.

answered Jan 3 at 13:46

David Heffernan

523k348391232

Thanks David, I've tried static and dynamic arrays, correctly allocated. The Handle is valid (it works in other functions of the dll). I think earlier calls to the DLL are not the problem (if I call another function instead it does not give an error) I will correct the BOOL and try

– Martín Castro Aguirrezabala
Jan 3 at 14:10

1

Changing the BOOL won't make a difference. Wherever your problem is, it's not in the code presented.

– David Heffernan
Jan 3 at 15:06

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

LONG maps to Longint, and LPLONG maps to ^Longint. So, you have translated that type correctly.

You have translated BOOL incorrectly though. It should be BOOL or LongBool in Delphi. You can use either, the former is an alias for the latter.

answered Jan 3 at 13:46

David Heffernan

523k348391232

Thanks David, I've tried static and dynamic arrays, correctly allocated. The Handle is valid (it works in other functions of the dll). I think earlier calls to the DLL are not the problem (if I call another function instead it does not give an error) I will correct the BOOL and try

– Martín Castro Aguirrezabala
Jan 3 at 14:10

1

Changing the BOOL won't make a difference. Wherever your problem is, it's not in the code presented.

– David Heffernan
Jan 3 at 15:06

add a comment |

LONG maps to Longint, and LPLONG maps to ^Longint. So, you have translated that type correctly.

You have translated BOOL incorrectly though. It should be BOOL or LongBool in Delphi. You can use either, the former is an alias for the latter.

answered Jan 3 at 13:46

David Heffernan

523k348391232

Thanks David, I've tried static and dynamic arrays, correctly allocated. The Handle is valid (it works in other functions of the dll). I think earlier calls to the DLL are not the problem (if I call another function instead it does not give an error) I will correct the BOOL and try

– Martín Castro Aguirrezabala
Jan 3 at 14:10

1

Changing the BOOL won't make a difference. Wherever your problem is, it's not in the code presented.

– David Heffernan
Jan 3 at 15:06

add a comment |

LONG maps to Longint, and LPLONG maps to ^Longint. So, you have translated that type correctly.

You have translated BOOL incorrectly though. It should be BOOL or LongBool in Delphi. You can use either, the former is an alias for the latter.

answered Jan 3 at 13:46

David Heffernan

523k348391232

LONG maps to Longint, and LPLONG maps to ^Longint. So, you have translated that type correctly.

You have translated BOOL incorrectly though. It should be BOOL or LongBool in Delphi. You can use either, the former is an alias for the latter.

answered Jan 3 at 13:46

David Heffernan

523k348391232

answered Jan 3 at 13:46

David Heffernan

523k348391232

answered Jan 3 at 13:46

David Heffernan

523k348391232

answered Jan 3 at 13:46

David Heffernan

523k348391232

Thanks David, I've tried static and dynamic arrays, correctly allocated. The Handle is valid (it works in other functions of the dll). I think earlier calls to the DLL are not the problem (if I call another function instead it does not give an error) I will correct the BOOL and try

– Martín Castro Aguirrezabala
Jan 3 at 14:10

1

Changing the BOOL won't make a difference. Wherever your problem is, it's not in the code presented.

– David Heffernan
Jan 3 at 15:06

add a comment |

Thanks David, I've tried static and dynamic arrays, correctly allocated. The Handle is valid (it works in other functions of the dll). I think earlier calls to the DLL are not the problem (if I call another function instead it does not give an error) I will correct the BOOL and try

– Martín Castro Aguirrezabala
Jan 3 at 14:10

1

Changing the BOOL won't make a difference. Wherever your problem is, it's not in the code presented.

– David Heffernan
Jan 3 at 15:06

Thanks David, I've tried static and dynamic arrays, correctly allocated. The Handle is valid (it works in other functions of the dll). I think earlier calls to the DLL are not the problem (if I call another function instead it does not give an error) I will correct the BOOL and try

– Martín Castro Aguirrezabala
Jan 3 at 14:10

Changing the BOOL won't make a difference. Wherever your problem is, it's not in the code presented.

– David Heffernan
Jan 3 at 15:06

add a comment |

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