Turbo Basic

Numbers in Turbo·BasicThe care and feeding of numbers constitutes an important part of every programmingsystem.Turbo Basic, in keeping with the BASIC tradition, has been designedto let you pretty much ignore technical considerations about internal numeric handling.If you never give a thought to such matters as calculation speed, precision,and memory requirement, your. programs will still. probably work as you expect.However, an understanding of the underlying issues will help you write ·programsthat are faster, more accurate, and require less memory.For efficiency, Turbo Basic stores and processes numbers in four different forms;that is, it supports four unique numeric "types": integers, long integers, singleprecisionfloating point, and double-precision floating point.IntegersThe simplest and fastest numbers rattling around inside Turbo Basic programs areintegers. To Turbo Basic, an integer is a number with no decimal point (whatmathematicians callwhole numbers} within the range -32,768 to 32,767. Thesevalues stem from the underlying 16-bit representation of integers: 32,768 is 2 15 •Although this range limits the usefulness of integers, there are almost certainly afew variables in every program you will write (such as the counters in FOR/NEXT .loops) that can function within these constraints. If so, using integers producesextremely fast and compact code. Your computer is uniquely comfortable performinginteger arithmetic (for example, it does it fast), and each number requires only2 bytes of memory.The Overflow debugging switch in the Options menu lets you create programsthat automatically check and report incidences of integer variable overflow.Umg IntegersIn a significant extension to Interpretive BASIC, Turbo Basic supports a numerictype known as long integers. To avoid round-off errors, long integers are the perfectdata type for financial applications. Like regular integers, long integers cannot containdecimal points. Unlike integers, however, they span a vast range, from- 2,147,483,648 to + 2,147,483,647 (-2 31 to 2 3 \ or - 2 billion to + 2 billion). Thedown side of this expanded range is that long integers· require 4 bytes of storage,and calculating with them takes longer than with integers;Turbo Basic: The Language 65