Relational Operators

[AliceB.Toklas]

In my Absolute Beginner's Guide to C book by Greg Perry
where it is instruction how relational operators work it gives the
following example:

int i = 5;

so the following statement is true:

int i == 1

Um, to me that says integer i is 5, and 5 is equal to 1.

Can someone help me understand this?
Thanks

[Ben Pfaff]

Al***********@g mail.com writes:

In my Absolute Beginner's Guide to C book by Greg Perry
where it is instruction how relational operators work it gives the
following example:

int i = 5;

so the following statement is true:

int i == 1

== is not a relational operator (it is an equality operator) and
the latter is not a statement, nor is it a valid declaration.
Are you sure that you've typed that in exactly as it appears in
the book?
--
"C has its problems, but a language designed from scratch would have some too,
and we know C's problems."
--Bjarne Stroustrup

[AliceB.Toklas]

On Mar 4, 4:55 pm, Ben Pfaff <[e-mail] rd.eduwrote:

AliceB.Tok...@g mail.com writes:

In my Absolute Beginner's Guide to C book by Greg Perry
where it is instruction how relational operators work it gives the
following example:

int i = 5;

so the following statement is true:

int i == 1

== is not a relational operator (it is an equality operator) and
the latter is not a statement, nor is it a valid declaration.
Are you sure that you've typed that in exactly as it appears in
the book?
--
"C has its problems, but a language designed from scratch would have some too,
and we know C's problems."
--Bjarne Stroustrup

Well my book lists == under relational operators, and my use of the
word statement was also directly from the book. Though, I'm quite
aware that I haven't got the lingo down. Anyway, there was one
mistake in my post, but I don't think it changes the fact it isn't a
valid declaration
int i = 5

the follow is true:

i == 1

[Ben Pfaff]

Al***********@g mail.com writes:

[My book states that, given]
int i = 5

the follow is true:

i == 1

Nope, it's not true. That is, i == 1 is false if i has the value
5. If your book really states that, it's just wrong.
--
"It wouldn't be a new C standard if it didn't give a
new meaning to the word `static'."
--Peter Seebach on C99

[Robert Gamble]

On Mar 4, 5:48 pm, AliceB.Tok...@g mail.com wrote:

In my Absolute Beginner's Guide to C book by Greg Perry
where it is instruction how relational operators work it gives the
following example:

int i = 5;

so the following statement is true:

int i == 1

Here is what your book actually says:

int i = 5;
int j = 10;
int k = 15;
int l = 5;
....
i == l
j < k
....

The author is saying that the value of the variable "i" is equal to
the value of the variable "l" (the letter l, not the number 1), etc.
The author could probably have picked better variable names.

Robert Gamble

[Richard Bos]

Al***********@g mail.com wrote:

On Mar 4, 4:55 pm, Ben Pfaff <[e-mail] rd.eduwrote:

AliceB.Tok...@g mail.com writes:

In my Absolute Beginner's Guide to C book by Greg Perry
where it is instruction how relational operators work it gives the
following example:

int i = 5;

so the following statement is true:

int i == 1

== is not a relational operator (it is an equality operator) and
the latter is not a statement, nor is it a valid declaration.
Are you sure that you've typed that in exactly as it appears in
the book?

Well my book lists == under relational operators,

Then the "Absolute Beginner's" in the title may well be a statement
about its author.

int i = 5

the follow is true:

i == 1

Of course not.

If the book really makes both of these errors, ditch it. Try K&R
instead.

Richard

[August Karlstrom]

Robert Gamble skrev:

On Mar 4, 5:48 pm, AliceB.Tok...@g mail.com wrote:

>In my Absolute Beginner's Guide to C book by Greg Perry
where it is instruction how relational operators work it gives the
following example:

[...]

The author is saying that the value of the variable "i" is equal to
the value of the variable "l" (the letter l, not the number 1), etc.
The author could probably have picked better variable names.

Indeed. To give an identifier the name l is very bad practice.
August

[August Karlstrom]

Ben Pfaff skrev:

== is not a relational operator (it is an equality operator)

Of course it is -- in the same sense as a car is a vehicle. Other
relational operators are <= and >=.
August

[Ben Pfaff]

August Karlstrom <fu********@com hem.sewrites:

Ben Pfaff skrev:

>== is not a relational operator (it is an equality operator)

Of course it is -- in the same sense as a car is a vehicle. Other
relational operators are <= and >=.

Not in C.

6.5.8 Relational operators
Syntax
1 relational-expression:
shift-expression
relational-expression < shift-expression
relational-expression shift-expression
relational-expression <= shift-expression
relational-expression >= shift-expression

6.5.9 Equality operators
Syntax
1 equality-expression:
relational-expression
equality-expression == relational-expression
equality-expression != relational-expression

--
Bite me! said C.

[August Karlstrom]

Ben Pfaff skrev:

August Karlstrom <fu********@com hem.sewrites:

>Ben Pfaff skrev:

>>== is not a relational operator (it is an equality operator)

Of course it is -- in the same sense as a car is a vehicle. Other
relational operators are <= and >=.

Not in C.

6.5.8 Relational operators
Syntax
1 relational-expression:
shift-expression
relational-expression < shift-expression
relational-expression shift-expression
relational-expression <= shift-expression
relational-expression >= shift-expression

6.5.9 Equality operators
Syntax
1 equality-expression:
relational-expression
equality-expression == relational-expression
equality-expression != relational-expression

Laughable
August