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Jian H. Li
Guest
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 Posted: Wed Feb 11, 2004 11:46 am Post subject: Can statements be written outside function body? |
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Hello,
As a beginner to C++, I need Your kind help to clarify the basic
concept. The sample C++ code as following:
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
Though both are legal C++ statement, //A & //B are different in this
code. //A is correct but //B is wrong. The same as statement //A, //B
is legal also, but //B can't occur outside function body. After moving
//B to position //C, the error alert disapeared. PLEASE EXPLAIN WHY.
Thank you.
Your Sincerely
Joe Li
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Guillaume Brocker
Guest
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| Posted: Wed Feb 11, 2004 11:53 am Post subject: Re: Can statements be written outside function body? |
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Jian H. Li wrote:
| Quote: | Hello,
As a beginner to C++, I need Your kind help to clarify the basic
concept. The sample C++ code as following:
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
Though both are legal C++ statement, //A & //B are different in this
code. //A is correct but //B is wrong. The same as statement //A, //B
is legal also, but //B can't occur outside function body. After moving
//B to position //C, the error alert disapeared. PLEASE EXPLAIN WHY.
|
You can declare a variable in the global scope (outside any function or
class body), but must put statements that are not declarations into a
function body. That's how C and C++ have been designed.
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John Harrison
Guest
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| Posted: Wed Feb 11, 2004 12:12 pm Post subject: Re: Can statements be written outside function body? |
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"Jian H. Li" <joe_li (AT) xinhuanet (DOT) com> wrote
| Quote: | Hello,
As a beginner to C++, I need Your kind help to clarify the basic
concept. The sample C++ code as following:
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
Though both are legal C++ statement, //A & //B are different in this
code. //A is correct but //B is wrong. The same as statement //A, //B
is legal also, but //B can't occur outside function body. After moving
//B to position //C, the error alert disapeared. PLEASE EXPLAIN WHY.
Thank you.
Your Sincerely
Joe Li
|
Because you can't put statements outside a function body.
If you could then when do you think the statements should be executed?
john
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David Harmon
Guest
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| Posted: Wed Feb 11, 2004 1:34 pm Post subject: Re: Can statements be written outside function body? |
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On Wed, 11 Feb 2004 12:12:24 -0000 in comp.lang.c++, "John Harrison"
<john_andronicus (AT) hotmail (DOT) com> was alleged to have written:
| Quote: | If you could then when do you think the statements should be executed?
|
Well, obviously it should be executed at the same time it would be if
you had written:
int i;
int j = i++;
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Jian H. Li
Guest
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| Posted: Thu Feb 12, 2004 2:20 am Post subject: Re: Can statements be written outside function body? |
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"John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote
| Quote: |
Because you can't put statements outside a function body.
If you could then when do you think the statements should be executed?
john
|
Not precise.
As shown below, code line //A is a legal statement outside a function body.
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
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John Harrison
Guest
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| Posted: Thu Feb 12, 2004 9:38 am Post subject: Re: Can statements be written outside function body? |
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"Jian H. Li" <joe_li (AT) xinhuanet (DOT) com> wrote
| Quote: | "John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote
Because you can't put statements outside a function body.
If you could then when do you think the statements should be executed?
john
Not precise.
As shown below, code line //A is a legal statement outside a function
body.
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
|
A is not a statement, it is a declaration. Declarations are legal outside of
function bodies, statements are not.
john
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osmium
Guest
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| Posted: Thu Feb 12, 2004 2:31 pm Post subject: Re: Can statements be written outside function body? |
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Jian H. Li writes:
| Quote: | Not precise.
As shown below, code line file://A is a legal statement outside a function
body.
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
|
Statements *and* declarations both end in semicolons. Look at the BNF to
make this believable.
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Ron Natalie
Guest
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| Posted: Thu Feb 12, 2004 4:45 pm Post subject: Re: Can statements be written outside function body? |
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"osmium" <r124c4u102 (AT) comcast (DOT) net> wrote
| Quote: |
Statements *and* declarations both end in semicolons. Look at the BNF to
make this believable.
Some statements end in semicolons. |
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Jian H. Li
Guest
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| Posted: Tue Mar 02, 2004 6:04 am Post subject: Re: Can statements be written outside a function body? |
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hello,
in iso/iec 14882, C++ standard, page 674~679 (A.5~A.7):
in A.5:
statement:
...
declaration-statement
...
declaration-statement:
block-declaration
A.6:
block-declaration:
simple-declaration
...
simple-declaration:
decl-specifier-seq(opt) init-declarator-list(opt) ;
decl-specifier-seq:
decl-specifier-seq(opt) decl-specifier
decl-specifier:
type-specifier
...
type-specifier:
simple-type-specifier
...
simple-type-specifier:
char
int
short
long
float
double
wchar_t
void
...
A.7:
init-declaration-list:
init-declarator
...
init-declarator:
declarator initializer(opt)
declarator:
direct-declarator
...
derect-declarator:
declarator-id
...
declarator-id:
id-expression
...
A.4:
id-expression:
unqualified-id
...
unqualified-id:
identifier
...
so, it's obvious "int i;" is a block-declaration, and also a statement.
Regards.
Jian H. Li
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Jian H. Li
Guest
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| Posted: Wed Mar 03, 2004 3:10 am Post subject: Re: Can statements be written outside function body? |
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"John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote
| Quote: | A is not a statement, it is a declaration. Declarations are legal outside of
function bodies, statements are not.
john
|
hello,
in iso/iec 14882, C++ standard, page 674~679 (A.5~A.7):
in A.5:
statement:
...
declaration-statement
...
declaration-statement:
block-declaration
A.6:
block-declaration:
simple-declaration
...
simple-declaration:
decl-specifier-seq(opt) init-declarator-list(opt) ;
decl-specifier-seq:
decl-specifier-seq(opt) decl-specifier
decl-specifier:
type-specifier
...
type-specifier:
simple-type-specifier
...
simple-type-specifier:
char
int
short
long
float
double
wchar_t
void
...
A.7:
init-declaration-list:
init-declarator
...
init-declarator:
declarator initializer(opt)
declarator:
direct-declarator
...
derect-declarator:
declarator-id
...
declarator-id:
id-expression
...
A.4:
id-expression:
unqualified-id
...
unqualified-id:
identifier
...
so, it's obvious "int i;" is a block-declaration, and also a statement.
Regards.
Jian H. Li
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Mike Wahler
Guest
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| Posted: Fri May 28, 2004 9:23 pm Post subject: Re: Can statements be written outside function body? |
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"John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote
| Quote: |
"Jian H. Li" <joe_li (AT) xinhuanet (DOT) com> wrote in message
news:c930b2b5.0402110346.2299dfbd (AT) posting (DOT) google.com...
Hello,
As a beginner to C++, I need Your kind help to clarify the basic
concept. The sample C++ code as following:
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
Though both are legal C++ statement, //A & //B are different in this
code. //A is correct but //B is wrong. The same as statement //A, //B
is legal also, but //B can't occur outside function body. After moving
//B to position //C, the error alert disapeared. PLEASE EXPLAIN WHY.
Thank you.
Your Sincerely
Joe Li
Because you can't put statements outside a function body.
If you could then when do you think the statements should be executed?
|
He probably believes "In the order they appear". Probably came
from BASIC.
-Mike
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Victor Bazarov
Guest
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| Posted: Fri May 28, 2004 9:34 pm Post subject: Re: Can statements be written outside function body? |
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Mike Wahler wrote:
| Quote: | "John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote in message
news:c0d62i$13k6oj$1 (AT) ID-196037 (DOT) news.uni-berlin.de...
"Jian H. Li" <joe_li (AT) xinhuanet (DOT) com> wrote in message
news:c930b2b5.0402110346.2299dfbd (AT) posting (DOT) google.com...
Hello,
As a beginner to C++, I need Your kind help to clarify the basic
concept. The sample C++ code as following:
int i; // A
i++; // B, error
int main()
{
i++; // C
return 0;
}
Though both are legal C++ statement, //A & //B are different in this
code. //A is correct but //B is wrong. The same as statement //A, //B
is legal also, but //B can't occur outside function body. After moving
//B to position //C, the error alert disapeared. PLEASE EXPLAIN WHY.
Thank you.
Your Sincerely
Joe Li
Because you can't put statements outside a function body.
|
You can, if they are declaration statements. The ++i is not
a statement by itself, it's an expression and it could be forced
to be evaluated, if you put it in a declaration/definition statement.
| Quote: |
If you could then when do you think the statements should be executed?
He probably believes "In the order they appear". Probably came
from BASIC.
|
But it is possible, generally, I believe. [this seems like a rather
old thread, though, maybe the question has already been answered...]
If you do
int i = 42;
int b = i++;
Then the (i++) part is going to be executed after the 'i's definition
and should probably do the trick...
Victor
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