Integer Types

• Read chapter 3.
• Integers and floats are just a little strange
  • C was built when memory was scarce.
  • C++ was built on top of C
  • So some items in C++ are a little complex.
• int
  • The basic data type to represent an integer in a program.
  • int i{0};
  • This is INT_MIN ≤ i ≤ INT_MAX
  • To get these predefined constants you must
  • #include <climits>
• Not as important but
  • sizeof(x) is a function
  • It returns the size of the object passed to it in bytes.
  • See This reference
  • Remember a byte is 8 bits.
• The long is another integer type.
  • The C++ standard states that the long is at least as "big" as an int
  • In most current implementations it is 64 bits.
  • I need it now because I want to compute $2^31$ which will not fit into an int.
• pow
  • this is a function as well.
  • It takes two parameters, or input values
  • The first is the base
  • The second is the exponent
  • It returns base^exponent
  • To do this, I need to include cmath
• When the result of a computation does not "fit"
  • This produces an incorrect computation.
  • Which is called numeric overflow.
• Just a few weird things
  • If you start a constant with 0, it thinks it is in octal.
    • 010 is not 10
  • 0x1f is a valid hex number
  • A short is usually a 16 bit number.
  • A char is a integer type
    • But they are weird with I/O
    • We will see more of this later.
  • An int is between $-2^{31} $ and $ 2^{31}-1$
  • An unsigned int is between $0 $ and $ 2^{32}-1$
  • There is a long long but in g++ this is just a long.