C Programming

DATA TYPES AND CONSTANTS
The four basic data types are

INTEGER
These are whole numbers, both positive and negative. Unsigned integers (positive values only) are supported. In addition, there are short and long integers.
The keyword used to define integers is,
```
	int
```
An example of an integer value is 32. An example of declaring an integer variable called sum is,
```
	int sum;
	sum = 20;
```
FLOATING POINT
These are numbers which contain fractional parts, both positive and negative. The keyword used to define float variables is,
```
	float
```
An example of a float value is 34.12. An example of declaring a float variable called money is,
```
	float money;
	money = 0.12;
```
DOUBLE
These are exponetional numbers, both positive and negative. The keyword used to define double variables is,
```
	double
```
An example of a double value is 3.0E2. An example of declaring a double variable called big is,
```
	double big;
	big = 312E+7;
```
CHARACTER
These are single characters. The keyword used to define character variables is,
```
	char
```
An example of a character value is the letter A. An example of declaring a character variable called letter is,
```
	char letter;
	letter = 'A';
```
Note the assignment of the character A to the variable letter is done by enclosing the value in single quotes. Remember the golden rule: Single character - Use single quotes.

Sample program illustrating each data type


	#include < stdio.h >

	main()
	{
		int   sum;
		float money;
		char  letter;
		double pi;

		sum = 10;		/* assign integer value */
		money = 2.21;		/* assign float value */
		letter = 'A';		/* assign character value */
		pi = 2.01E6;		/* assign a double value */

		printf("value of sum = %d\n", sum );
		printf("value of money = %f\n", money );
		printf("value of letter = %c\n", letter );
		printf("value of pi = %e\n", pi );
	}


	Sample program output
	value of sum = 10
	value of money = 2.210000
	value of letter = A
	value of pi = 2.010000e+06