how to read "fig 5-1"

I would say "figure five dash one". For a printer or typesetter, the symbol which should come between the 5 and the 1 is called a "figure dash". It is not a hyphen. A dash is longer than a hyphen and is used differently.

"figure five dash one"

contrex,

what are the odds of 2 people answering a question simultaneously at this early hour?

What early hour? It was 10:32 AM here in England when I answered. There are lots of us Brits out and about at that time on a Tuesday. I had been at work for 2 hours. I'm just about to have my lunch now. At this moment it is 12:15 PM.

its so friggin' early here that i forgot the concept of time zones...

That computer has an "off" switch!

so it does, so it does...

hey, what'd you have for lunch?

4 oz hamburger in a sesame bun with red leaf salad and a glass of orange juice

So, what's the difference between hyphen and dash?

well, you can't hyphen off to the pub for a quick pint

djjd62, could you tell me what you meant, please? Thanks.

He was making a joke about a different meaning of the word "dash".

Ignore him.

To answer your question:

Many people do not know the difference between a hyphen and a dash.

The difference is important for certain people: Writers, journalists, and people who work in printing, publishing, proofreading and typesetting, and people ?- like yourself ?- who wish to correctly read aloud the numbers of illustrations, figures, tables, etc in technical and scientific publications. It might be useful to know when giving or taking dictation using English texts.

(What follows is a simplified explanation)

Hyphens and dashes differ in two ways:-

(1) In appearance:-

The standard dash is called an "em dash", because it is as wide as a capital M in whatever typeface is being used.

A hyphen in that typeface will be half the width of an em dash.

(2) In use.

(a) Hyphens
A hyphen is used to form compound words, and there is no space between the hyphen and the words either side:-

The building will re-open in December.
This an award-winning book.
His name is Smithers-Jones.

(There is a tendency in modern English to drop the hyphen from many compound words. 100 years ago people wrote of machine-guns or joy-riders, now they might well write about machine guns and joyriders.)

(b) Dashes
The most common use of em dashes is instead of commas when setting off a parenthetical comment. For example:

Item 12, the broken CPU, is to be repaired today.

can be replaced by

Item 12 ?- the broken CPU ?- is to be repaired today.

Or to span two clauses in a sentence:

I'm thinking of going to the pub ?- do you want to come?

Many people surround em dashes with spaces. Some do not.

The dash you noticed in the caption for a figure is called a "figure dash" which is so named because it is the same width as a digit, at least in fonts with digits of equal width. The figure dash is used when a dash must be used within numbers, for example with figure or telephone numbers: figure 5-1, telephone number 634-5789. Figure dashes are not usually surrounded by spaces.

On typewriters and perhaps in some very rudimentary word-processing programs, a dash is made by simply typing two hyphens. Many web browsers do not display dashes correctly.

So to decide whether a symbol is a hyphen or a dash you may need to consider how it is being used.

Now I've got it. Thank you so much, Contrex.

I am glad to help.

You may also hear of "en dashes" which are narrower than em dashes. These may be ignored unless you intend to study printing. The difference between dashes and hyphens is as I described above.