Inline vs Macro: Difference and Comparison

Inline and macro are functions used in C++ and C computer programming. Mostly the inline function is used more than a macro.

Key Takeaways

1. Inline functions are expanded at compile time, while the preprocessor expands macros before compilation.
2. Inline functions provide type safety and perform automatic type conversions, whereas macros do not.
3. Macros can cause side effects due to multiple evaluations, while inline functions do not.

Inline vs Macro

Inline is a normal function that is defined by the inline keyword and can easily access the members of the class to improve the function. Macro is defined by the #define keyword and although it belongs to the C and C++ language, it is used in the former. It is error-prone but flexible.

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.

Macro is defined by the #define keyword. It is almost never used in C++, and it is used in C language more. They are more flexible, but they are error-prone.

Comparison Table

Parameters of Comparison	Inline	Macro
Definition	Inline is a normal function used in C++ language defined by the keyword “Inline”.	Macro is a function used in C language that is defined by the keyword “#define”.
Access of class members	Can easily access the members of the class.	Cannot access the members of the class.
Debugged	The 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.
Termination	It 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.

The function can be defined either inside or outside the class. And can be terminated by the symbol of the curly brace.

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 the required conversions are presented correctly. This function is not widely used, mostly, it is used in the C++ language but is not required in competitive programming.

What is Micro?

Macro is expanded by a preprocessor in a program therefore, it is also called a preprocessor directive. This function is defined by the “#define” keyword.

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.

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.

Main Differences Between Inline And Macro

1. Inline is almost never used in competitive programming, while on the other hand, Macro is widely used in competitive programming.
2. 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.

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