Type Checking, Storage Management, Elementary Types

Static type checking

• Number, order, and types of all arguments and results
  
• data type of every object described by variable name
  
• type of each constant
  
• choices?
  
  • leave type unchecked
    
  • flag error and use exception handler
    
  • coercion (type change)
    

Dynamic type checking

• type information must be kept during execution
  
• must be done using software
  

Storage management

• storage allocation
  
• access path creation
  

garbage -- lose path, before storage retrieved

dangling reference -- recover storage and fail to destroy path

Data Representation:

• bit: 0, 1
  (two values)
  
• byte == 8 bits
  2^8
  
• word
  

Elementary Types

Boolean

char: byte -- 256

• creation
  
• deletion
  
• equality (= or ==)
  
• assignment (:= or =)
  
• ord(char)
  
• char(int)
  

integer:

• - (negation)
  
• remainder (mod or %)
  

binary representation - integers:

real:

• similar operations to integer
  

binary representation - reals:

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