Difference Between Inline And Macro (With Table)

Inline and macro are functions used in C++ and C computer programming. Mostly the inline function is used than a macro. Macro is almost always unnecessary in a C++ language as they are error-prone, they cannot access the private members of a class. Both functions may look similar but they are definitely not. Both the function have their advantages and disadvantages.

Inline vs Macro

The main difference between the Inline function and the macro function is that the inline function is a short function that is analyzed by a compiler while on the other hand, a macro is expanded by the preprocessor. Indeed, inline can access the members of a class while the macro function cannot access the members of a class.

Inline is a normal Function. The function is defined by the inline keyword. It can easily access the members of the class. It improves the function. Indeed, is easy to use. It is used in the C++ computer programming language. Mostly it is defined inside or outside the class and is terminated by the symbol of curly brace.

Macro is defined by the #define keyword. It is almost never used in C++, it is used in C language more. They are more flexible but they are error-prone. And macro is expanded when the program processing is done by the preprocessor. Macro can not access the class’s members.

Comparison Table Between Inline And Macro

Parameters of ComparisonInlineMacro
DefinitionInline is a normal function used in C++ language defined by the keyword “Inline”.Macro is a function used mostly in C language that is defined by the keyword “#define”.
Access of class membersCan easily access the members of the class.Cannot access the members of the class.
DebuggedThe program can be easily debugged.The program cannot be easily debugged.
Where to define?Either inside or outside the class.At the beginning of the program.
TerminationIt is terminated by a symbol, a curly brace at the end.It is terminated by a new line rather than a symbol.

What is Inline?

Inline is a normal function that is used in the C++ computer programming language. It is defined by the inline keyword. It is a short-length function that is expanded through compilation. Inline is not a command, it is rather a request.

The function can be defined either inside or outside the class. And can be terminated by the symbol of the curly brace. With the use of the inline function, at the compiling time, the whole code of the inline function gets inserted or substituted. It is done at the point of the inline function call by the C++ compiler. Also, it can easily access all the members of the class.

The advantage of the inline function is that the function call overhead doesn’t occur. When the function is called, it saves the overhead of push/pop variables on the stack and also saves the overhead of a return call from a function.

The arguments in the case of an inline function, are evaluated only once and required conversions are presented correctly. This function is not widely used, mostly it is used in the C++ language but it is not required in competitive programming. Although, it is safe and easy to use.

What is Micro?

Macro is expanded by a preprocessor in a program therefore it is also called preprocessors directive. This function is defined by the “#define” keyword. The preprocessor examines the program before the program compilation. It replaces all the macro calls directly within the macro code, by the macro definition.  The instruction expands at the time of its call during the processing. It is very flexible.

Macro can be expanded irrespective of the fact that they are syntactically correct. From the macro expansion problems, the compile phase of the macro function will result in report errors. It is defined at the very beginning of a program and can be terminated by a new line. The advantage with macro is that the arguments in macro are evaluated every time a macro function is used in the program.

Macros cannot access the class’s members, which is a disadvantage. And it cannot be debugged easily. Indeed, it can cause some side effects because of the expansion as the input expressions are copied everywhere they appear in the pattern. The macro function is not as useful as the inline function, still, it is widely used in competitive programming. Mostly it is used in C programming rather than C++. It looks like a function call which it is not.

Main Differences Between Inline And Macro

  1. Inline improves the function and is safe to use and therefore it is more useful than a macro.
  2. The keyword which is used to define an inline function is “inline”. For the macro, the “#define” keyword is used to define it.
  3. The class’s data member can be accessed through the inline function. While they cannot get accessed by the macros.
  4. The program can be easily debugged in the inline functions while it’s not easy to debug in the case of macros.
  5. Inline is almost never used in competitive programming while on the other hand, Macro is widely used in competitive programming.
  6. The arguments in the case of inline are evaluated only once while in the case of macro the arguments are evaluated every time the macro function is used in the program.

Conclusion

Inline function is more safe and easy to use therefore it is used in C++ computer language programming all the time. It can access all the members of the class and is easy to debug too. Although it is not used as widely as macros is. Indeed, it is not used in competitive programming.

Macros are widely used. It is used in context and can be expanded irrespective of the fact that they are syntactically correct. It is not easy to debug. And it is defined at the beginning of the program and can be terminated by a new line.

References

  1. https://link.springer.com/chapter/10.1007/978-3-322-87867-0_8
  2. https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10091/100910H/Inline-measurement-for-quality-control-from-macro-to-micro-laser/10.1117/12.2255824.short
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