Recommendation for defining a macro in C language

Learn: What is the macro in C/C++ language? Here I am writing some of the recommendations; you should keep in mind while defining a macro.

Example of Macros:

#define MAX 100
#define PI 2.14

Recommendations/rules to define a Macro

  1. Macros are usually used for constants, so whenever you require a constant type value you should use macros to:
    • Make execution fast - because Marcos expends at compile time not at rum time.
    • Save memory - like variable, macros do not take spaces in the memory.
    • Make easy for changes - Yes, instead of hard coded values macros are easy to change. Make change once, compile the program and it will affect all places where used.
  2. enerally Macros are written in uppercase letters- it’s just a recommendation not a rule, you should write Marco names in uppercase to differentiate with other objects.
  3. Macros contains three words 1) #define 2) Macro_Name and 3) value. There must be spaces between the words.
  4. There must not be trailing semicolon (;), that means you cannot use semicolon after the statement (so, remember this).

Examples on defining MACRO

Example 1 - Here we are defining two MACROS with integer and string value

#include <stdio.h>

#define MAX_TRY 10
#define CITY "New, Delhi"

int main()
    printf("value of MAX_TRY: %d\n",MAX_TRY);
    printf("value of CITY: %s\n",CITY);
    return 0;


value of MAX_TRY: 10
value of CITY: New, Delhi

Example 2 - Here we are replacing "printf" with "PRINT"

#include <stdio.h>

#define PRINT printf

int main()
    PRINT("Hello world!\n");
    PRINT("How are you?\n");
    //we can also use printf
    printf("Hey! this is printf\n");
    return 0;


Hello world!
How are you?
Hey! this is printf

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