Global Variables in SDI
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Hi My Doubt is how to call this glboal variables in other forms... Well i declared like this 1. Declare "static CString g_m" in APP.h 2.Declare CString CISApp::g_m = NULL in App.cpp 3.Use CISApp::g_m where ever you want to use
To access 'g_m' from another cpp file you need to declare 'g_m' as an extern in that file - see my first post. In my first post I suggested that you have dedicated files for this purpose, Globals.h and Externs.h. If you do this each time a cpp file needs to access a global you can just include the 'Externs.h' so it makes life easier. Also it anables you to quickly see all your globals at one time, you could add the extern declaration to each file that needs to access the global but as your project grows it will probably get messy very quickly. :)
Ali
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To access 'g_m' from another cpp file you need to declare 'g_m' as an extern in that file - see my first post. In my first post I suggested that you have dedicated files for this purpose, Globals.h and Externs.h. If you do this each time a cpp file needs to access a global you can just include the 'Externs.h' so it makes life easier. Also it anables you to quickly see all your globals at one time, you could add the extern declaration to each file that needs to access the global but as your project grows it will probably get messy very quickly. :)
Ali
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OK, perhaps I've missed something. :) What is the linker error that you get?
Ali
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OK, perhaps I've missed something. :) What is the linker error that you get?
Ali
Usually a global variable is defined in one source file (you did it in a header one). :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
Usually a global variable is defined in one source file (you did it in a header one). :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
Usually a global variable is defined in one source file (you did it in a header one). :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]:-O Really, I've been doing it that way for years! (I suppose that's how I was taught to declare variables in embedded systems.) Does it matter?
Ali
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:-O Really, I've been doing it that way for years! (I suppose that's how I was taught to declare variables in embedded systems.) Does it matter?
Ali
- If you don't include such header in any source file then you get 'undifined symbol' by the linker.
- If you include the header in multiple source files then you get 'multiple definitions' by the linker.
- If you include the header into exactly one source file then the linker will cheer you.
Of course this is going on my ... :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
- If you don't include such header in any source file then you get 'undifined symbol' by the linker.
- If you include the header in multiple source files then you get 'multiple definitions' by the linker.
- If you include the header into exactly one source file then the linker will cheer you.
Of course this is going on my ... :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]CPallini wrote:
If you include the header into exactly one source file then the linker will cheer you.
That's what I do, I declare my global variable in a header called 'Globals.h', then include it just once! :thumbsup: Then I declare it as extern in Externs.h and include it wherever I want to use it ..... :) The linker is happy, but I thought you considered it a bad habit or bad style and I wondered why ..... maybe I missunderstood ...... :)
Ali
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CPallini wrote:
If you include the header into exactly one source file then the linker will cheer you.
That's what I do, I declare my global variable in a header called 'Globals.h', then include it just once! :thumbsup: Then I declare it as extern in Externs.h and include it wherever I want to use it ..... :) The linker is happy, but I thought you considered it a bad habit or bad style and I wondered why ..... maybe I missunderstood ...... :)
Ali
Well, if you define the global variable into a source file then you lower the probabilities of duplicate inclusion... :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
i solved it... but error occurs when i transfer the data to edit box... m_txtlog=g_MyVariable; UpdateData(FALSE); Error occurs while displayin
hellogany wrote:
Error occurs
Which error ? Please be specific, we can't see what is displayed on your screen.
Cédric Moonen Software developer
Charting control [v3.0] OpenGL game tutorial in C++ -
Well, if you define the global variable into a source file then you lower the probabilities of duplicate inclusion... :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
Well While Debugging, i m able to get the value .... But couldnt able to display in edit control. Its throws Assertin Error
Please post the (relevant) code. :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
Ya.. i was tryin to use this.. This works well in Dialog Apps.. but am in SDi now ..Its throws Assertion Failed Error
hellogany wrote:
Its throws Assertion Failed Error
What line of what file is asserting?
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"Man who follows car will be exhausted." - Confucius
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how does to update to textbox.. I am Able to get date... is UpdateData(FALSE) Works fine in SDI(FormView) ???
hellogany wrote:
is UpdateData(FALSE) Works fine in SDI(FormView) ???
Why are you using
UpdateData()? Without fully understanding what it does and how to use it, it will only cause you grief. UseSetWindowText()instead."One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"Man who follows car will be exhausted." - Confucius
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Please post the (relevant) code. :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
m_txtlog=g_MyVariable; UpdateData(FALSE); m_txlog is the edit control i am using the above code in oncreate function...
You cannot do that in the on
OnCreatemethod, since controls not yet exist. :)If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
CPallini wrote:
If you include the header into exactly one source file then the linker will cheer you.
That's what I do, I declare my global variable in a header called 'Globals.h', then include it just once! :thumbsup: Then I declare it as extern in Externs.h and include it wherever I want to use it ..... :) The linker is happy, but I thought you considered it a bad habit or bad style and I wondered why ..... maybe I missunderstood ...... :)
Ali
The problem here is that you have a terminology issue. You declare the variable in HEADER file (something.h) that can be freely included in SOURCE files (*.c / *.cpp)
extern int g_MyVariable
Where you and other have an issue is that you implement the variable in another .h file, that you actually treat like a source file. So, your compiler builds some cpp file, that is the only file including this special header. As long as you are disciplined about this, you'll be fine. But anyone else coming along will be puzzled. Some day you'll make a mistake... If you put the actual implementation
int g_MyVariable = 0;
in a source file, then you can't make this mistake. OK, you can, but any line like:
#include "globalvars.cpp"
is going to be really obvious. I hope that helps a little... Iain.
I have now moved to Sweden for love (awwww).
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The problem here is that you have a terminology issue. You declare the variable in HEADER file (something.h) that can be freely included in SOURCE files (*.c / *.cpp)
extern int g_MyVariable
Where you and other have an issue is that you implement the variable in another .h file, that you actually treat like a source file. So, your compiler builds some cpp file, that is the only file including this special header. As long as you are disciplined about this, you'll be fine. But anyone else coming along will be puzzled. Some day you'll make a mistake... If you put the actual implementation
int g_MyVariable = 0;
in a source file, then you can't make this mistake. OK, you can, but any line like:
#include "globalvars.cpp"
is going to be really obvious. I hope that helps a little... Iain.
I have now moved to Sweden for love (awwww).