Data Types

• Programming language can store data as different data types
• The code for an integer is " int "
• Integers are whole numbers only
• The code for a real (or float) is " real "
• A real number is a number that has a decimal point
• The code for Boolean is " bool "
• A Boolean data type only has one of two values , TRUE or FALSE
• The code for a character is " char "
• A character is a single letter , number or symbol
• The code for a String is " string "
• Each data type has a different amount of memory
• What is the typical amount of memory taken up by an integer?


  2 bytes or 4 bytes
• What is the typical amount of memory taken up by a Real?

  4 bytes or 8 bytes
• What is the typical amount of memory taken up by a Boolean?

  1 bit is needed but 1 byte is usually used
• What is the typical amount of memory taken up by a Character?

  1 byte
• What is the typical amount of memory taken up by a String?

  1 byte for every character in the string
• Using the correct data types makes code more memory efficient , robust (hard to break) and predictable
• Weakly typed programming languages try to convert data types to avoid errors , but this can lead to unpredictable results
• Strongly typed programming languages won't try to convert data types and so will produce more errors but also more predictable results
• Casting is used to change the data type
• Languages have functions that let you manually convert between data types - this is known as casting
• what does the int("1") command do?

  It converts the string value of "1" to the integer value of 1
• What does the real(1) command do?

  It converts the integer value of 1 to the real value of 1.0
• What does the bool(1) command do?

  It converts the integer value of 1 to the Boolean value of True
• what does the str(True) command do?

  It converts the Boolean value of True into the string value of "True"
• What does the ASC(b) command do?

  It converts the character 'b' into the ASCII number 98
• What does the CHR(98) command do?

  It converts the ASCII number 98 into the character 'b'