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C tokens, Identifiers and Keywords are the basics in a C program. All are explained in this page with definition and simple example programs.
1. C tokens:
- C tokens are the basic buildings blocks in C language which are constructed together to write a C program.
- Each and every smallest individual units in a C program are known as C tokens.
C tokens are of six types. They are,
- Keywords (eg: int, while),
- Identifiers (eg: main, total),
- Constants (eg: 10, 20),
- Strings (eg: “total”, “hello”),
- Special symbols (eg: (), {}),
- Operators (eg: +, /,-,*)
C tokens example program:
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int main() { int x, y, total; x = 10, y = 20; total = x + y; printf ("Total = %d \n", total); } |
where,
- main – identifier
- {,}, (,) – delimiter
- int – keyword
- x, y, total – identifier
- main, {, }, (, ), int, x, y, total – tokens
Do you know how to use C token in real time application programs? We have given simple real time application programs where C token is used. You can refer the below C programs to know how to use C token in real time program.
2. Identifiers in C language:
- Each program elements in a C program are given a name called identifiers.
- Names given to identify Variables, functions and arrays are examples for identifiers. eg. x is a name given to integer variable in above program.
Rules for constructing identifier name in C:
- First character should be an alphabet or underscore.
- Succeeding characters might be digits or letter.
- Punctuation and special characters aren’t allowed except underscore.
- Identifiers should not be keywords.
3. Keywords in C language:
- Keywords are pre-defined words in a C compiler.
- Each keyword is meant to perform a specific function in a C program.
- Since keywords are referred names for compiler, they can’t be used as variable name.
C language supports 32 keywords which are given below. Click on each keywords below for detail description and example programs.
auto | double |
int | struct |
const | float |
short | unsigned |
break | else |
long | switch |
continue | |
signed | void |
case | enum |
register | typedef |
default | goto |
sizeof | volatile |
char | extern |
return | union |
do | |
static | while |