[SOLVED] Initialize / use pointer
lazarus / 62-General

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pcurtis · 2021-11-05 07:38

I have this type and a var

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i type 
Pndu_WLAN_CONNECTION_PARAMETERS = ^Tndu_WLAN_CONNECTION_PARAMETERS;  
Tndu_WLAN_CONNECTION_PARAMETERS = record    wlanConnectionMode:
Tndu_WLAN_CONNECTION_MODE;    strProfile: LPCWSTR;    pDot11Ssid:
Pndu_DOT11_SSID;    pDesiredBssidList: Pndu_DOT11_BSSID_LIST;   
dot11BssType: Tndu_DOT11_BSS_TYPE;    dwFlags: DWORD;  end; var 
pConnectionParameters : Pndu_WLAN_CONNECTION_PARAMETERS; 
Every time I try to assign values (for example)

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  
pConnectionParameters^.dwFlags := 0; 
I get a SIGSEGV.

What am I missing?

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440bx · 2021-11-05 07:45

Quote from: pcurtis on November 05, 2021, 08:38:29 amI have this type
and a var

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i type 
Pndu_WLAN_CONNECTION_PARAMETERS = ^Tndu_WLAN_CONNECTION_PARAMETERS;  
Tndu_WLAN_CONNECTION_PARAMETERS = record    wlanConnectionMode:
Tndu_WLAN_CONNECTION_MODE;    strProfile: LPCWSTR;    pDot11Ssid:
Pndu_DOT11_SSID;    pDesiredBssidList: Pndu_DOT11_BSSID_LIST;   
dot11BssType: Tndu_DOT11_BSS_TYPE;    dwFlags: DWORD;  end; var 
pConnectionParameters : Pndu_WLAN_CONNECTION_PARAMETERS; 
Every time I try to assign values

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  
pConnectionParameters^.dwFlags := 0; 
I get a SIGSEGV.

What am I missing?
You have a pointer to a record _definition_ but you don't have a
record to point to.

have something like this:Code: Pascal  [Select][+][-]window.onload =
function(){var x1 = document.getElementById("main_content_section");
if (x1) { var x = document.getElementsByClassName("geshi");for (var i
= 0; i var  TnduVar : Tndu_WLAN...etc_record; PconnectionParameters :
... {as you have it now } ... {somewhere in the code}  
PConnectionParameters := @TndvVar; { NOW you can set the dwFlags to
something }   PConnectionParameters^.dwFlags := {whatever you want }

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Thaddy · 2021-11-05 07:49

Looks like the record is not allocated. Call new() (and later
dispose())
Something like:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var 
pConnectionParameters : Pndu_WLAN_CONNECTION_PARAMETERS;begin // just
to show the
logic. New(pConnectionParameters); pConnectionParameters^.dwFlags :=
0; // and somewhere later. Dispose(pConnectionParameters); end.
Alternatively you can declare the var as the T version instead of the
P version. That also gives you an accessible record and does not need
new/dispose.

If the record already exists use the code by 440bx (our posts crossed)

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pcurtis · 2021-11-05 08:23

Thanks all