J
James
Ian said:
I don't get it. Brackets aren't required to compile, they just extend
the scope of the loop. Did I miss something?
James
I don't get it. Brackets aren't required to compile, they just extend
the scope of the loop. Did I miss something?
James
D
Daniel T.
I do not know what is meant by Mr.Lippman. Since I do not have a paper
copy, I can not give an exact page number but the exact exercise number
is
Exercises Section 2.4
Exercise 2.22: The following program fragment, while legal, is an
example of poor style. What problem(s) does it contain? How would you
improve it?
for (int i = 0; i < 100; ++i)
// process i[/QUOTE]
I looked around on the 'net a bit but couldn't find any references (and
I don't have the book.) Without more context, one cannot say that the
above is "poor style" in any way. If the magic number '100' appears in
come other location such that if it changes in one place, it must also
change here, then using '100' instead of a const int is poor style.
J
Jim Langston
James said:
Yes. They're saying the following program:
int main()
{
for ( int i = 0; i < 100; ++i )
// process i
}
will not compile without at least a ; or {} at the end of the for block. A
bit pedantic since this is only a code snippet.
M
mlimber
utab said:
Please tell me you didn't download it from one of those pirated sites
that are spammed here every week or so. If so, I cannot help you.
Cheers! --M
J
Jim Langston
utab said:
That excersice is bogus AFAIC because there is not enough information given
to determine if that is in fact poor style. The simplest way to make it
better style is:
enum { ArrayElements = 100 };
for ( int i = 0; i < ArrayElements; ++i )
{
// process i, etc..
}
just to get rid of the magic number.
Other than that, whoever wrote that exercise exepects you to be a mind
reader to figure out what the heck he was talking about, unless the section
before that explained why he didn't like it (a personal choice it would
seem)
R
Ron Natalie
No, they make a compound statement. A statement is REQUIRED after theJames said:
for loop. You either need { } or a ; or some other legal form of a
statemnt.
A
alexisbietti
for (int i = 100; --i >= 0
{
// process i
}
is superior than the other solution : comparing an integer to 0 is more
effective than comparing to any other value.
Of course, reverse loops may have side effects, it may break your app !
{
// process i
}
is superior than the other solution : comparing an integer to 0 is more
effective than comparing to any other value.
Of course, reverse loops may have side effects, it may break your app !
C
Clark S. Cox III
for (int i = 100; --i >= 0
{
// process i
}
is superior than the other solution : comparing an integer to 0 is more
effective than comparing to any other value.
More effective in what way?
This seems to mean that it is *less* effective in the general case.
P
Pete Becker
Jim said:
"Better" style depends on context. If I'm writing a throwaway utility to
do something 100 times, I'm not going to waste time and space creating
an enum. There's nothing wrong with writing a hard-coded upper limit in
that context.
P
Pete Becker
Clark said:
He's applying a processor-specific micro-optimization.
S
Salt_Peter
James said:
Nope, you didn't miss anything unless you have compound statements.
What is required is the semicolon:
for(int i = 0; i < 100; ++i)
process i;
N
Noah Roberts
Pete said:
enums take space?
T
Thomas Tutone
Noah said:
In the source file (which is what Pete was presumably referring to).
Not in the compiled code.
Best regards,
Tom
J
Jim Langston
Pete Becker said:
I agree. Myself, I would most likely code it exactly like the original
sample.
P
Pete Becker
Noah said:
Yes. The code that uses enums is longer than the code that doesn't.
J
Jim Langston
for (int i = 100; --i >= 0
{
// process i
}
is superior than the other solution : comparing an integer to 0 is more
effective than comparing to any other value.
Of course, reverse loops may have side effects, it may break your app !
Of course, though, if you're iterating through an array of 100 elements,
with your code you're now iterating backwards, unless you do 100-n or
something, which makes it less effective.
If someone is worried about an extra clock cycle, they should be doing it in
assembly in the first place.
A
Andrew Koenig
As noted, the exercise appears at the end of section 2.4. If you read
section 2.4, you will find that the exercise is answered in the first few
paragraphs of that section.
So the real point of the exercise is to get you to read the text
G
Gernot Frisch
Being pedantic again:
process i; is systax error. Write:
process(i);
A
alexisbietti
Even better solution :
for (int i = 100; i--; )
{
// process i
}
Saves a comparison operation, as is tests only whether the return value
of i-- (which is i before decrementation) is zero or not.
(e-mail address removed) a écrit :
for (int i = 100; i--; )
{
// process i
}
Saves a comparison operation, as is tests only whether the return value
of i-- (which is i before decrementation) is zero or not.
(e-mail address removed) a écrit :
V
Victor Bazarov
Gernot said:
Not unless 'process' is a macro defined as 'std::cout <<'...
V