MoreDataRepresentation

# MoreDataRepresentation - More Data Representation More Data...

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More Data Representation Beta Draft - Do not distribute © 2001, By Randall Hyde Page 87 More Data Representation Chapter Four 4.1 Chapter Overview Although the basic machine data objects (bytes, w ords, and double w ords) appear to represent nothing more than signed or unsigned numeric v alues, we can emplo y these data types to represent man y other types of objects. This chapter discusses some of the other objects and their internal computer representation. This chapter be gins by discussing the ﬂ oating point (real) numeric format. After inte ger representation, oating point representation is the second most popular numeric format in use on modern computer sys - tems 1 . Although the ﬂ oating point format is some what comple x, the necessity to handle non-inte ger calcu - lations in modern programs requires that you understand this numeric format and its limitations. Binary Coded Decimal ( BCD) is another numeric data representation that is useful in certain conte xts. Although BCD is not suitable for general purpose arithmetic, it is useful in some embedded applications. The principle benefi t of the BCD format is the ease with which you can con v ert between string and BCD for - mat. When we look at the BCD format a little later in this chapter , you’ ll see wh y this is the case. Computers can represent all kinds of dif ferent objects, not just numeric v alues. Characters are, unques - tionably , one of the more popular data types a computer manipulates. In this chapter you will tak e a look at a couple of dif ferent w ays we can represent indi vidual characters on a computer system. This chapter dis - cusses tw o of the more common character sets in use today: the ASCII character set and the Unicode charac - ter set. This chapter concludes by discussing some common non-numeric data types lik e pix el colors on a video display , audio data, video data, and so on. Of course, there are lots of dif ferent representations for an y kind of standard data you could en vision; there is no w ay tw o chapters in a te xtbook can co v er them all. (And that’ s not e v en considering specialized data types you could create). Ne v ertheless, this chapter (and the last) should gi v e you the basic idea behind representing data on a computer system. 4.2 An Introduction to Floating Point Arithmetic Inte ger arithmetic does not let you represent fractional numeric v alues. Therefore, modern CPUs sup - port an approximation of r eal arithmetic: ﬂ oating point arithmetic. A big problem with ﬂ oating point arith - metic is that it does not follo w the standard rules of algebra. Ne v ertheless, man y programmers apply normal algebraic rules when using ﬂ oating point arithmetic. This is a source of defects in man y programs. One of the primary goals of this section is to describe the limitations of ﬂ oating point arithmetic so you will under - stand ho w to use it properly .

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## This note was uploaded on 08/08/2011 for the course CS 101 taught by Professor Jitenderkumarchhabra during the Summer '11 term at National Institute of Technology, Calicut.

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MoreDataRepresentation - More Data Representation More Data...

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