multiple c files in visual studio 6 project
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Hi i want to create a project in visual studio 6 that contains multipe C source files and header files but i cant understand how a file can access a function or a variable declared in the other file ? and i want to know if its right to add #includes for the standard libraries in all files ? thanks
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Hi i want to create a project in visual studio 6 that contains multipe C source files and header files but i cant understand how a file can access a function or a variable declared in the other file ? and i want to know if its right to add #includes for the standard libraries in all files ? thanks
Ayman Mashal wrote:
but i cant understand how a file can access a function or a variable declared in the other file ?
What you need to do is provide a function prototype of your function that will be declared in your header file. Then the function body will be in the cpp file. In the cpp file in which you would like to use this function, simply include the header file. If the function is defined somewhere in a cpp file, then the linker will do its job ;).
Ayman Mashal wrote:
and i want to know if its right to add #includes for the standard libraries in all files ?
A good practice is to include only the files you need in your file.
Cédric Moonen Software developer
Charting control [v1.1] -
Hi i want to create a project in visual studio 6 that contains multipe C source files and header files but i cant understand how a file can access a function or a variable declared in the other file ? and i want to know if its right to add #includes for the standard libraries in all files ? thanks
Ayman Mashal wrote:
i cant understand how a file can access a function or a variable declared in the other file ?
For functions, Cedric Moonen has answered you. For variables, look at the keyword
externfor doing this.Ayman Mashal wrote:
i want to know if its right to add #includes for the standard libraries in all files ?
It is perfectly safe to
#includethe libraries in all the files, until they are guarded with#ifndef,#defineand#endifto prevent it from being included multiple times.
Nobody can give you wiser advice than yourself. - Cicero ப்ரம்மா
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Ayman Mashal wrote:
i cant understand how a file can access a function or a variable declared in the other file ?
For functions, Cedric Moonen has answered you. For variables, look at the keyword
externfor doing this.Ayman Mashal wrote:
i want to know if its right to add #includes for the standard libraries in all files ?
It is perfectly safe to
#includethe libraries in all the files, until they are guarded with#ifndef,#defineand#endifto prevent it from being included multiple times.
Nobody can give you wiser advice than yourself. - Cicero ப்ரம்மா
lets say that i have header.h file that contains types,variables,defines declarations and that i have main.h file that include header.h file and main.h is included in many source files . now when i try to build the project i get that the variables in header.h already defined in the obj file . so how can i deal with this ? thanks
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lets say that i have header.h file that contains types,variables,defines declarations and that i have main.h file that include header.h file and main.h is included in many source files . now when i try to build the project i get that the variables in header.h already defined in the obj file . so how can i deal with this ? thanks
You need to surround your header file with include guards. Something similar to this:
#ifndef MYFILE_H
#define MYFILE_H... The code of your header comes here
#endif
You need to replace MYFILE_H by something unique in your project. In general, you can simply use the filename.
Cédric Moonen Software developer
Charting control [v1.1] -
lets say that i have header.h file that contains types,variables,defines declarations and that i have main.h file that include header.h file and main.h is included in many source files . now when i try to build the project i get that the variables in header.h already defined in the obj file . so how can i deal with this ? thanks
in headers, you shouldn't define variables. you should only declare extern variables, that means to the compiler that the variable has been defined somewhere in a c/cpp file ; it's the linker job to synthetize this.
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You need to surround your header file with include guards. Something similar to this:
#ifndef MYFILE_H
#define MYFILE_H... The code of your header comes here
#endif
You need to replace MYFILE_H by something unique in your project. In general, you can simply use the filename.
Cédric Moonen Software developer
Charting control [v1.1] -
Why not only
#if _MSC_VER > 1000 #pragma once #endif // _MSC_VER > 1000at the top of the .h-file? Seems to work fine.ensger wrote:
at the top of the .h-file? Seems to work fine.
Yes, it will. Way suggested by Cedric is one of the ways. And using pragma's make code dependent on particular compiler.
Prasad Notifier using ATL | Operator new[],delete[][^]
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Hi i want to create a project in visual studio 6 that contains multipe C source files and header files but i cant understand how a file can access a function or a variable declared in the other file ? and i want to know if its right to add #includes for the standard libraries in all files ? thanks
Ayman Mashal wrote:
and i want to know if its right to add #includes for the standard libraries in all files ?
Technically you can, but it's bad practice. Put them all in a single file common to all of your project. Since those files are not going to be changing, take advantage of precompiled headers by turning on precompiled headers for that single file.
"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15
"Judge not by the eye but by the heart." - Native American Proverb