C Tutorials
| Tokens |
A token is either a keyword, an identifier, a constant, a string literal. For example
printf
(
"Hello World"
;
| Semicolons |
The semicolon is a statement terminator.Each individual statement must be ended with a semicolon. It indicates the end of one logical entity. For example, following are two different statements:
printf("\n Hello World");
return 0;
| Comments |
Comments are like helping text in your C program and they are ignored by the compiler. They start with /* and terminates with the characters */ as shown below:
/* My first C Program */
We can not have comments with in comments and they do not occur within a string or character literals.
| Identifiers |
A C identifier is a name used to identify a variable, function, or any other user-defined item. An identifier starts with a letter A to Z or a to z or an underscore _ followed by zero or more letters, underscores, and digits (0 to 9).
C does not allow punctuation characters such as @, $, and % within identifiers. C is a case sensitive programming language. Thus This and this are two different identifiers in C. Here are some examples of acceptable identifiers:
wind abc a_name a_123
cpro50 _var x cName x1y
| Keywords |
C has predefined list of keywords which cannot used for any other purpose like varibale name or any other identifier. Following is the list of keywords in C.
| auto | static | long | switch |
| break | enum | register | typedef |
| case | extern | return | union |
| char | float | short | unsigned |
| const | for | signed | void |
| continue | goto | sizeof | volatile |
| default | if | else | while |
| do | int | struct | _Packed |
| double |
| White Spaces |
A line containing only whitespace, possibly with a comment, is known as a blank line, and a C compiler totally ignores it.
Whitespace is the term used in C to describe blanks, tabs, newline characters and comments. Whitespace separates one part of a statement from another and enables the compiler to identify where one element in a statement, such as int, ends and the next element begins. Therefore, in the following statement:
int class;
There must be at least one whitespace character (usually a space) between int and class for the compiler to be able to distinguish them.
name = wind + trainers
No whitespace characters are necessary between name and =, or between = and wind, although we are free to include some if you wish for readability purpose.
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