C Tokens
In C program, each word and punctuation are called as Tokens. Basically, tokens are the building blocks for the C code.
The compiler usually breaks the C programs into smaller units and proceeds to the various stages of compilation which are called as Tokens.
The following are the 6 tokens in C programming such as:
- Identifiers
- Keywords
- Constants
- Strings
- Operators
- Special Symbols
C identifiers are used to identify a variable, function, or any other user-defined item. C is a case-sensitive programming language.
An identifier starts with a letter A to Z, a to z or an underscore ‘_’ followed by letters or numbers, digits (0 to 9) and underscores.
Following are some of the examples of identifiers,
Example
Spark_databox spark _Databox spark_123
i spark12databox SparkDatabox _12spark
Note: Identifiers are not valid if it started by number.
Keywords
Keywords are predefined, reserved words in C language and each keyword has specified features. Keywords have special meaning to the compilers. These keywords cannot be used as identifiers (variables or constants) in the program.
Example
| auto | case | break | char |
continue
| do
| default
| const
|
double
| if
| else
| enum
|
extern
| for
| goto
| float
|
int
| long
| return
| register
|
signed
| static
| sizeof
| short
|
unsigned
| volatile
| void
| union
|
typedef
| struct
| switch
| while
|
Constants are similar to a variable except that their value never changes during execution of the code.
Constants in C are the fixed values that remains same during the execution of the program. The following are some of the features of Constants,
- Constants are also called as literals.
- Constants always start with upper-case names.
- Constants can be used along with any type of data types.
The constant keyword defines a constant in C.
Syntax
constant type constant_name;
Example
#include
main() {
const int LENGTH = 10;
const int BREADTH = 5;
int area = LENGTH * BREADTH;
printf("Area of Rectangle is %d", area);
return 0;
}Output
Area of Rectangle is 50
Note: The const can be put either before or after the data type is possible. The following two lines of code are same.
float const VALUE = 100;
or
const float VALUE = 100;
Constants are characterized into two types namely,
- Numeric Constants
- Integer Constants
- Real Constants
- Character Constants
- Single Character Constants
- String Constants
- Backslash Character Constants
Integer Constant is the sequence of digits. They are three types namely,
- Decimal Integer
- Octal Integer
- Hexadecimal Integer
Example
Decimal Integer: 25, -40, 0, 1931.90
Octal Integer: 033, 064
Hexadecimal Integer: 0X3
Real Constant
A number contains two parts such as real and floating point constants
Example
99.25
99 – real part
25- fractional part
Single Character Constant
It contains single character enclosed with single quotes (‘ ‘). For example, the character ‘4’ is not same as an integer 4. Character constant has a specific set of integer values corresponding to the characters are known as ASCII values (American Standard Code of Information Interchange).
Example:
‘x’, ‘9’, ’,’ ,‘H’
Strings are sequence of characters enclosed with double quotes (“ ”) which may contain numbers, letters, special characters and blank spaces. In C language, “A” and ‘A’ are different. “A” is a string whereas ‘A’ is a character.
Example:
“SparkDatabox”, “2020”, “F”
Backslash character Constant
C supports some character constant with the backslash in front of it. The following are the list of backslash characters has a specific meaning to the compiler. They are also called as “Escape Sequence”.
\a
| Beep sound
|
\b
| backspace
|
\f
| Form feed
|
\r
| Carriage return
|
\t
| Horizontal tab
|
\v
| Vertical tab
|
\’
| Single quote
|
\”
| Double quote
|
\\
| Backslash
|
\0
| Null
|
Defining Constants
In following ways, we define C constants:
- Using #define preprocessor
- Using const keyword
#define Preprocessor
We define constants like shown below:
#include
#define LENGTH 5
#define WIDTH 3
#define NEWLINE '\n'
int main() {
int Area;
Area = LENGTH * WIDTH;
printf("Area of Rectangle : %d", Area);
printf("%c", NEWLINE);
return 0;
}
Output:
Area of Rectangle : 15
The const Keyword
The const prefix is used as prefix for the variables such as,
const type variable = value;
Example:
#include
int main() {
const float RADIUS = 10;
const char NEWLINE = '\n';
float area;
area = 2 * 3.14 * RADIUS ;
printf("value of area : %f", area);
printf("%c", NEWLINE);
return 0;
}
Output:
value of area : 62.799999
Note: For good programming practices, we always use CAPITALS to define the constants.
+91-4446311234
+1-6502652492
+91-7530088009
