Variables & Data Types

Variables

• What are variables?
  • holds information that can be changed
• Why use variables?
  • programs with information that's predetermined is not very useful
• How to use variables?
  • declare variables
  • initialize variables
  • set, change, or display variables

Data types

• What are data type's?
  • data types specifies what type of information is stored by the variable
  • C has many type's available, they are listed here
• Why use data type's?
  • so the program knows how much memory to allocate and how to interpret the allocated memory
  • C requires all variables to be type'd
    • some programming languages don't require type'ing
    • here's an article on dynamic vs static type'ing, you can just read the conclusion
• How to use data type's?
  • to declare an integer number: int i_am_an_integer;
  • to declare a character: char i_am_a_char;
  • to declare a decimal number: float i_am_a_float;
  • to declare a decimal number with higher precision: double i_am_a_double;

Variables Example

#include <stdio.h>

main() {

    // declare variables

    int i_am_an_integer;

    char i_am_a_char;

    float i_am_a_float;

    double i_am_a_double;

    // initialize variables

    i_am_an_integer = 11;

    i_am_a_char = 'c';

    i_am_a_float = 1.23;

    i_am_a_double = 1.23;

}