CODEWITHSUNDEEP
c++operators
witherspoon
witherspoon

Reputation: 141

C++: Asterisks, Ampersand and Star?

Recently I came across this video on Programming Paradigms and the prof. used terms like Asterisks, Star, and Ampersand.

This was what how he used those operators:

int i = 37;
float f = *(float*)&i;

And how he voiced line 2 while writing it:

Float "f" equals asterisk float star, ampersand of i

I understand what asterisk and ampersand mean, but what is the significance of using star here? Is it synonymous to asterisk?

Upvotes: 9

Views: 20072

Answers (5)

I am not englishman
I am not englishman

Reputation: 69

& parameter = print address

& type = ref() : that means I want this guy's new name not duplicate.

* parameter = get value from this address

* type = store address (pointer variable)

Upvotes: 0

Troubadour
Troubadour

Reputation: 13431

The * after the float is used to form a type. Very often when referring to a pointer type in words people will say "star" after the type rather "pointer", eg. "malloc returns a void star". I've never heard anyone use "asterisk" to refer to a type.

The * at the start is used to de-reference the pointer thereby accessing the value it points to (interpreted as a float due to the following cast). Again, in my own experience I've never heard anyone use "asterisk" here. People just tend to say "de-reference" to describe the operation being performed.

I wouldn't read too much into it. There are two different contexts here as you rightly spotted and as long as you understand what they mean from a C++ point of view then that's fine.

Upvotes: 11

SigTerm
SigTerm

Reputation: 26439

Is it synonymous to asterisk?

Yes. Shift+8 on MY windows keyboard. Your example demonstrates why you shouldn't try to read C++ program aloud symbol by symbol. "Equals" in C++ is "==". "=" is assignment. Plus he forgot to tell about parentheses and semicolon. At this point (4 mistakes in single line of code) he could've written the damn thing silently.

It would have been much better if the dude read this part:

float f = *(float*)&i;

somewhat like this:

"Take pointer to i, C-style cast it into pointer to float, dereference, and assign value to float variable f". Makes much more sense that "star/asterisk" gibberish.

P.S. If you really love tongue twisters, you could try reading aloud any code that uses boost, iostreams, operator <<, casts, bitwise operations and "camel case" to distinguish between classes and methods. Such exercise will not improve your programming skills, of course...

Upvotes: 1

Denis Kreshikhin
Denis Kreshikhin

Reputation: 9430

float f = *(float*)&i;

In this case left * and right * has different sematics. Left * means value getting by refernce. Right * declares reference type.

Upvotes: 3

TonyK
TonyK

Reputation: 17124

I think the presenter just wanted to avoid an awkward silence while he wrote out the code. As far as I know, there is no difference between asterisk and star in this context.

Upvotes: 0

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