CSI 2

Basic data types in C

• Integers:
  • char - characters (or digits), 1 byte
  • short - 2 bytes
  • int - 4 bytes
  • long - 8 bytes
  • long long - at least 8 bytes
  • unsigned - modifier, makes the value >= 0
  • signed - modifier, allows the value to be negative
• Real numbers:
  • float - 4 bytes, IEEE 754
  • double - 8 bytes, IEEE 754
  • long double - at least 10 bytes, IEEE 754

Char

The char value is stored as a number indicating the ASCII code of that character.

'\' - escape character

Special characters

• \n - New line
• \r - Carriage return
• \t - Horizontal Tab
• \\ - Backslash

Variables

Declaration - define a variable with a name and find a place for it in memory. Value of the variable before assignment is going to be undefined (aka "junk")

int x;

Assignment - assign a value to the variable (store a value in memory in the corresponding address)

x = 1;

Initialization - combination of declaration and assignment

int x;
x = 1;
// or
int x = 1;

Variable identifiers

Identifiers can consist of the Latin letters (A-Za-z), underscores (_) and digits (0-9), although the first character cannot be a digit.

Identifiers cannot shadow C reserved words (if, for, etc.)