Suky asked in 電腦與網際網路程式設計 · 1 decade ago

# 程式語言C 不懂書上的意思

A float number is typically a 32-bit quantity,with at least six significant digits

and magnitude generally between about 10的負38次方 and 10的正38次方

Rating
• 1 decade ago

Mukesh_Singh_Nick...yahoo.com writes:

What is meant by the "most significant digits" in the following

statement?

Don't bother with markup like this. Usenet news is a plain text

medium. People sometimes use markers for humorous effect

(e.g. really? ) but don't try to effect the llok of

your post with HTML or similar.

With %g and %G, the precision modifier determines the maximum number

of significant digits displayed.

You say "most" at the top but the quote has "maximum" so I am i bit

about what is bothering you. The precision determines how

much of number gets represented. Obviously only the most significant

digits are used but you can say "no more than X digits". There may

be other stuff printed, because %g might use scientific notation, but

the precision limits the number of significant digits printed. The

number you give is a maximum because fewer may be sufficient:

4.0e30 using %.3g prints "4e+30"

4.3e30 using %.1g prints "4e+30"

4.3e30 using %.2g prints "4.1e+30"

The statement appears here:

http://www.cppreference.com/stdio/printf.html

Look like a C++ reference. This may lead you astray if you are using

it for C. Read the C FAQ instead: http://c-faq.com/

Also, what do we mean by the magnitude of a floating point number?

I understand that the magnitude of an integral is equal to its

absolute value. However, I do not understand the meaning of the

magnitude of a floating point.

It usually means exactly the same -- the absolute value. It certainly

does in the quote you cite from K&R:

A float number is typically a 32-bit quantity, with at

least six significant digits and magnitude generally between about

10^(-38) and 10^(+38).

Source: K & R, Page 9, Second Edition

Ben.

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Source(s): [][][]Play_Coll_Leo[][][]=PC
• 1 decade ago

可以來個中文嗎?

看不太懂ㄝ

解釋給我我問的最後一句^^