CSE 2031 Lecture 3

• Integer types:
  
  • char
    
  • short
    
  • int
    
  • long
    
• Floating point types:
  
  • float
    
  • double
    
  • long double
    

Char

• 1 byte long
  
• char<= short<=int<=long
  
• denote characters in single quotes
  
• \0 is a null character
  
• char *b = "TEST";
  
  • is a string writer (assumption)
    
• EOF
  
  • Reads as -1
    
    • Which is an array of ones
      
• getchar() reads a byte of unsigned chars and stores 4 bytes to represent them
  
  • the promotion to int is done as a signed char
    
  • This is because of things like EOF
    
• A signed char
  
  • Fills the other bytes with the first bit of the signed char
    
  • If it is signed and starts with 0
    
    • It is non negative
      
  • If it starts with 1
    
    • It is a negative number
      
• An unsigned
  
  • Does not fill the other 3 bytes with the first bit but with all 0's when promoted to an int
    

Declarations

• when you declare a variable in C it is visible throughout the score of the brackets that it is withheld
  
• if you want a variable to be visible throughout a program put it above the main
  
• to make one variable local to a file use the word 'static'
  

String

• an array of char
  
• there is no 'String' in C
  

Arrays

• to declare an array in C
  
  • use type name[size]
    
    • example: int number[10]
      
• you can initialize an array w/o a specified size
  
  • char s[] = {'h','e','l','l','o','\0', 'q'}
    
  • printf("%s /n", s}
    
    • returns 'hello'
      
      • note there is no q, that is because null character was before it
        

printF

• %d prints integers
  
• %s prints char characters
  
  • Prints until it finds a null character
    
  • Null character is \0
    
• %p prints the address
  

Console

• Od –cb filename
  
  • Describes a file in bits