Identifiers And Keywords in C language : CodeWithMe

 

Keywords and Identifiers

Identifiers:

Identifiers are the names given to various program elements such as constants,

variables, function names and arrays etc. Every element in the program has its own

distinct name but one cannot select any name unless it conforms to valid name in C

language. Let us study first the rules to define names or identifiers.

 

 

Identifiers are defined according to the following rules:

1. It consists of letters and digits.

2. First character must be an alphabet or underscore.

3. Both upper and lower cases are allowed. But each a word in different case will be teated different example. Hello and hello will be different.

4. Except the special character underscore ( _ ), no other special symbols can be

used.

 

Keywords In C language

 

Keywords are reserved words which have standard, predefined meaning in C. They

cannot be used as program-defined identifiers. There 32 keywords in C Here is the list of keywords :

1. do
2. while 
3. char
4. typedef
5. auto
6. case
7. switch
8. else
9. if
10. int
11. printf
12. double 
13. struct 
14. break
15. static
16. long 
17. enum 
18. register
19.  extern
20.  return 
21. union 
22. const
23. float short
24. unsigned 
25. continue
26. for 
27. signed 
28. void
29. default 
30. goto 
31. sizeof
32. volatile

Escape Characters :

There are some non-printable characters that can be printed by preceding them with ‘\’ backslash character. Within character constants and string literals, you can write a variety of escape sequences. Each escape sequence determines the code value for a single character. You can use escape sequences to represent character codes: 

•  you cannot otherwise write (such as \n)
•   that can be difficult to read properly (such as \t)