inline Functions in C

[krisvamsi22]

Hi,

I want to know about inline functions in C, why they are used? How they works? Advantages and disadvantages of using them? And if any practical examples.... I tried in Google search but couldnt find relevant data.

Please help me by giving some explanation or link where I can get explanation.

Thanks in advance,

Vamsi Krishna

[gpraghuram]

Hi,

I want to know about inline functions in C, why they are used? How they works? Advantages and disadvantages of using them? And if any practical examples.... I tried in Google search but couldnt find relevant data.

Please help me by giving some explanation or link where I can get explanation.

Thanks in advance,

Vamsi Krishna

if u #define a function and use it then it will be sort of inline function in C.
But it dosent provide all benefits provided by the inline functions in c++.

Thanks
Raghuram

[Banfa]

if u #define a function and use it then it will be sort of inline function in C.
But it dosent provide all benefits provided by the inline functions in c++.

The some of the more developed C compilers (mainly ones that support C++ as well) support real inlining although this is an extension of the standard.

For instance the Microsoft C/C++ compiler supports inlining in C, but it has to be explicitly enabled and functions have to be marked with the __inline keyword, the __ indicating it is a platform extension rather than part of the C language.

The advantage of inlining is that it makes the code quicker because it saves the function call overhead by putting the functions code directly into the code where it is called rather than actually making a function call.

The disadvantage of function inlining is that it tends to make the code larger because of all the repeated copies of the function.

The best candidates for function inlining are functions which are small, a few code lines (i.e. the function call overhead is a large portion of the time the function takes to run) and which are called often (the saved time is quite small so it only makes a real difference if you save it a lot of times).


I have also used the method gpraghuram describes of replacing functions with function like macros.


However which ever method you use it is worth profiling the application first to see where you may be able to make savings.

[krisvamsi22]

The some of the more developed C compilers (mainly ones that support C++ as well) support real inlining although this is an extension of the standard.

For instance the Microsoft C/C++ compiler supports inlining in C, but it has to be explicitly enabled and functions have to be marked with the __inline keyword, the __ indicating it is a platform extension rather than part of the C language.

The advantage of inlining is that it makes the code quicker because it saves the function call overhead by putting the functions code directly into the code where it is called rather than actually making a function call.

The disadvantage of function inlining is that it tends to make the code larger because of all the repeated copies of the function.

The best candidates for function inlining are functions which are small, a few code lines (i.e. the function call overhead is a large portion of the time the function takes to run) and which are called often (the saved time is quite small so it only makes a real difference if you save it a lot of times).


I have also used the method gpraghuram describes of replacing functions with function like macros.


However which ever method you use it is worth profiling the application first to see where you may be able to make savings.

Hi Thanks a lot for the answer, if inline functions are doing same as what a macro function is doing then what could be the difference between defining a function as a macro and defining it as __inline. What is the advantage of using inline over defining a function as macro? I have seen many functions defined as inline in Embedded device driver programing, what role it plays there?

Thanks in advance for the help

[gpraghuram]

inline offers many advantages over macros.(To get more info on this do a saerch in the net with rem macros vs inline).
When u say inline it is always not guaranteed whether it will be inlined and it depends purely on the compiler optimization

Thanks
Raghu

[dharanidhar]

#define _INITHW_C_SRC

does the above represent a inline function?
If a function is defined in one of the files and we want to use it in another,is it in this case we use inline function?

[gpraghuram]

#define _INITHW_C_SRC

does the above represent a inline function?
If a function is defined in one of the files and we want to use it in another,is it in this case we use inline function?

No...This is not a inline function.
Inline functions are basicallu used to increase the speed that is by avoiding the function call.(you have to read the post by Banfa)

Raghuram