Variables and Types

#Tutorial2# 

Data types

C has several types of variables, but there are a few basic types:

• Integers - whole numbers which can be either positive or negative. Defined using char, int, short, long or long long.
• Unsigned integers - whole numbers which can only be positive. Defined using unsigned char, unsigned int, unsigned short, unsigned long or unsigned long long.
• Floating point numbers - real numbers (numbers with fractions). Defined using float and double.
• Structures - will be explained later, in the Structures section

#define BOOL char
#define FALSE 0
#define TRUE 1

C uses arrays of characters to define strings, and will be explained in the Strings section.



Defining variables
For numbers, we will usually use the type int,
 which an integer in the size of a "word" the default number size of the
 machine which your program is
compiled on. On most computers today, it is a 32-bit number, which means
 the number can range from -2,147,483,648 to 2,147,483,647.


To define the variables foo and bar, we need to use the following syntax: 
int foo;
int bar = 1;
The variable foo can be used, but since we did not initialize it, we don't know what's in it. The variable bar contains the number 1.


Now, we can do some math. Assuming a, b, c, d, and e are variables, we can simply use plus, minus and multiplication operators
in the following notation, and assign a new value to a: 
int a = 0,b = 1,c = 2,d = 3, e = 4;
a = b - c + d * e;
printf("%d", a); /* will print 1-2+3*4 = 11 */