What are macros in c?

Answer 1

In C macros are a piece of code that is replaced by its value whenever it called from.

Syntax for defining a macro is :

# define Macro_Name Value

As:

# include<stdio.h>

# define three 3

int main(){

printf("%d", three);

return 0;

}

output: 3.

In above example three is a macro and its value is 3.

The place for defining macros are same as including a header file in a program.

Answer 2

Macros are very common and often used in C Programming to declare constants, such as strings, addresses, or any other values such as maximum number of elements in an array, and so on. For those who are not familiar with them, Macros are declared by the #define keyword. Macros are also used to define some basic functionality given a set of 1 or more typeless parameters, similarly to an inline function.

There are some benefits by using Macros:

1. Code maintainability: Using a macro to define a constant provides an easy and correct method to ensure that if this value needs to be updated; all instances of this value will be automatically updated. Otherwise, the program may behave incorrectly, and even crash.
2. Code readability: Specifying a macro name is much more readable and understandable to someone who needs to read the code, than a plain number or address.

There are also some disadvantages:

1. Hard to extend: If the macros become complex and a change is required, any errors you introduce may yield vague compilation errors by the compiler, and always, the error line number points to the start of the macro.
2. Hard to debug: Debuggers often do not provide clear access and step ability to a code inside macros.