gaspersic/freeCodeCamp
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Small edits (#29888)

Browse Source
This commit is contained in:
Connor
2019-02-20 04:24:41 +00:00
committed by Manish Giri
parent 551c97feb1
commit 2424f7892b
1 changed files with 5 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
guide/english/c/macros/index.md
View File

@ -3,7 +3,9 @@ title: Macros in C
---
## Macros in C
A macro is a piece of code with a given name. When the name is used, it is replaced by the content of the macro. The `#define` keyword is used to define new macros. It's followed by a name and a content. By convention, macro names are written in uppercase. There are two type of macros: `Object-like` macros and `Function-like` macros.
A macro is a piece of code with a given name. When the name is used, it is replaced by the content of the macro. This is handled by the C Preprocessor, before compilation.
The `#define` keyword is used to define new macros. It's followed by a name and a content. By convention, macro names are written in uppercase. There are two type of macros: `Object-like` macros and `Function-like` macros.
#### Why Macros?
The C compiler will go through your code and replace every occurrence of a macro with it's value. This begs the question, what is the point of using macros? The answer: macros are a tool for the programmer, not for the program.
@ -12,9 +14,8 @@ If you have the number `365` hard-coded into your program, it becomes difficult
It's also beneficial if you have many instances of the same thing. If you'd used `2018` as the year in multiple places in your program, and then the year changed to `2019`, you would have to go and find every single line containing `2018` and change it, hoping you didn't miss any. With the macro `#define YEAR 2018`, you can simply change the value of the macro and be confident all of the values have been updated accordingly.
#### Defining macros
The `#define` keyword is used to define new macros. It's followed by a name and a content, but no equals sign. By convention, macro names are written in uppercase.
The `#define` keyword is used to define new macros. It's followed by a name and the replacement code, but no equals sign. By convention, macro names are written in uppercase.
```C
#define PI 3.14
@ -24,7 +25,7 @@ If you use the macro this way:
```C
printf("Value of PI: %d", PI);
```
Is the same as write this:
Is the same as writing this:
```C
printf("Value of PI: %d", 3.14);
```