Is the address of a local variable a constexpr? Announcing the arrival of Valued Associate...
Is the address of a local variable a constexpr?
What does the "x" in "x86" represent?
When -s is used with third person singular. What's its use in this context?
What would be the ideal power source for a cybernetic eye?
What makes black pepper strong or mild?
How do I stop a creek from eroding my steep embankment?
Why don't the Weasley twins use magic outside of school if the Trace can only find the location of spells cast?
How to assign captions for two tables in LaTeX?
What are 'alternative tunings' of a guitar and why would you use them? Doesn't it make it more difficult to play?
The logistics of corpse disposal
Gastric acid as a weapon
How to deal with a team lead who never gives me credit?
Should gear shift center itself while in neutral?
What is the musical term for a note that continously plays through a melody?
What is the correct way to use the pinch test for dehydration?
Is there a "higher Segal conjecture"?
Right-skewed distribution with mean equals to mode?
Is high blood pressure ever a symptom attributable solely to dehydration?
Is 1 ppb equal to 1 μg/kg?
If 'B is more likely given A', then 'A is more likely given B'
I am not a queen, who am I?
Antler Helmet: Can it work?
How can I fade player when goes inside or outside of the area?
Why was the term "discrete" used in discrete logarithm?
Is the address of a local variable a constexpr?
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)
The Ask Question Wizard is Live!
Data science time! April 2019 and salary with experience
Should we burninate the [wrap] tag?What are the differences between a pointer variable and a reference variable in C++?When should you use constexpr capability in C++11?Undefined reference to static constexpr char[]const vs constexpr on variablesDoes static constexpr variable make sense?Difference between `constexpr` and `const`Unique address for constexpr variableenum vs constexpr for actual static constants inside classesConstexpr placement new?constexpr unique id, compiles with clang but not with gcc
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ height:90px;width:728px;box-sizing:border-box;
}
In Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 (Section 10.4.5 Address Constant Expressions), he uses a code example where the address of a local variable is set to a constexpr variable. I thought this looked odd, so I tried running the example with g++ version 7.3.0 and was unable to get the same results. Here is his code example verbatim (although slightly abridged):
extern char glob;
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
When I run this, I get:
error: ‘(const char*)(& loc)’ is not a constant expression
Is something happening with g++ that I'm not aware of, or is there something more to Bjarne's example?
c++ c++11 constexpr memory-address
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
|
show 2 more comments
In Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 (Section 10.4.5 Address Constant Expressions), he uses a code example where the address of a local variable is set to a constexpr variable. I thought this looked odd, so I tried running the example with g++ version 7.3.0 and was unable to get the same results. Here is his code example verbatim (although slightly abridged):
extern char glob;
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
When I run this, I get:
error: ‘(const char*)(& loc)’ is not a constant expression
Is something happening with g++ that I'm not aware of, or is there something more to Bjarne's example?
c++ c++11 constexpr memory-address
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
2
Clearly, &loc can't be a constexpr. However, these lines of code don't appear on my kindle version. He does show a constexpr for the address of a "C" style string in a local function. That's legal since these are in global space while loc is an argument on the stack and not constant. Is that example what you are referring to?
– doug
1 hour ago
@doug check section 10.4.5 Address Constant Expressions. I'll update the question to make this more clear. Also, my example is abridged
– johnnyodonnell
57 mins ago
2
char locis a locally declared character that is not static. The next timef()is called there is no guaranteelocwill have the same address. 10.4.5 makes that distinction between an address assigned by the linker and those assigned by the compiler. 2013 Stroustrup - The C++ Programming Language 4th Edition.pdf
– David C. Rankin
56 mins ago
1
@DavidC.Rankin it looks like your version (a pdf) is different from mine (a hard-copy). This must have been a mistake and was updated by the time your pdf was created.
– johnnyodonnell
46 mins ago
2
Yes, I was kinda scratching my head as to where&globcame from, but&locwas identifiable.
– David C. Rankin
43 mins ago
|
show 2 more comments
In Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 (Section 10.4.5 Address Constant Expressions), he uses a code example where the address of a local variable is set to a constexpr variable. I thought this looked odd, so I tried running the example with g++ version 7.3.0 and was unable to get the same results. Here is his code example verbatim (although slightly abridged):
extern char glob;
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
When I run this, I get:
error: ‘(const char*)(& loc)’ is not a constant expression
Is something happening with g++ that I'm not aware of, or is there something more to Bjarne's example?
c++ c++11 constexpr memory-address
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
In Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 (Section 10.4.5 Address Constant Expressions), he uses a code example where the address of a local variable is set to a constexpr variable. I thought this looked odd, so I tried running the example with g++ version 7.3.0 and was unable to get the same results. Here is his code example verbatim (although slightly abridged):
extern char glob;
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
When I run this, I get:
error: ‘(const char*)(& loc)’ is not a constant expression
Is something happening with g++ that I'm not aware of, or is there something more to Bjarne's example?
c++ c++11 constexpr memory-address
c++ c++11 constexpr memory-address
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
edited 41 mins ago
johnnyodonnell
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
asked 1 hour ago
johnnyodonnelljohnnyodonnell
378114
378114
2
Clearly, &loc can't be a constexpr. However, these lines of code don't appear on my kindle version. He does show a constexpr for the address of a "C" style string in a local function. That's legal since these are in global space while loc is an argument on the stack and not constant. Is that example what you are referring to?
– doug
1 hour ago
@doug check section 10.4.5 Address Constant Expressions. I'll update the question to make this more clear. Also, my example is abridged
– johnnyodonnell
57 mins ago
2
char locis a locally declared character that is not static. The next timef()is called there is no guaranteelocwill have the same address. 10.4.5 makes that distinction between an address assigned by the linker and those assigned by the compiler. 2013 Stroustrup - The C++ Programming Language 4th Edition.pdf
– David C. Rankin
56 mins ago
1
@DavidC.Rankin it looks like your version (a pdf) is different from mine (a hard-copy). This must have been a mistake and was updated by the time your pdf was created.
– johnnyodonnell
46 mins ago
2
Yes, I was kinda scratching my head as to where&globcame from, but&locwas identifiable.
– David C. Rankin
43 mins ago
|
show 2 more comments
2
Clearly, &loc can't be a constexpr. However, these lines of code don't appear on my kindle version. He does show a constexpr for the address of a "C" style string in a local function. That's legal since these are in global space while loc is an argument on the stack and not constant. Is that example what you are referring to?
– doug
1 hour ago
@doug check section 10.4.5 Address Constant Expressions. I'll update the question to make this more clear. Also, my example is abridged
– johnnyodonnell
57 mins ago
2
char locis a locally declared character that is not static. The next timef()is called there is no guaranteelocwill have the same address. 10.4.5 makes that distinction between an address assigned by the linker and those assigned by the compiler. 2013 Stroustrup - The C++ Programming Language 4th Edition.pdf
– David C. Rankin
56 mins ago
1
@DavidC.Rankin it looks like your version (a pdf) is different from mine (a hard-copy). This must have been a mistake and was updated by the time your pdf was created.
– johnnyodonnell
46 mins ago
2
Yes, I was kinda scratching my head as to where&globcame from, but&locwas identifiable.
– David C. Rankin
43 mins ago
2
2
Clearly, &loc can't be a constexpr. However, these lines of code don't appear on my kindle version. He does show a constexpr for the address of a "C" style string in a local function. That's legal since these are in global space while loc is an argument on the stack and not constant. Is that example what you are referring to?
– doug
1 hour ago
Clearly, &loc can't be a constexpr. However, these lines of code don't appear on my kindle version. He does show a constexpr for the address of a "C" style string in a local function. That's legal since these are in global space while loc is an argument on the stack and not constant. Is that example what you are referring to?
– doug
1 hour ago
@doug check section 10.4.5 Address Constant Expressions. I'll update the question to make this more clear. Also, my example is abridged
– johnnyodonnell
57 mins ago
@doug check section 10.4.5 Address Constant Expressions. I'll update the question to make this more clear. Also, my example is abridged
– johnnyodonnell
57 mins ago
2
2
char loc is a locally declared character that is not static. The next time f() is called there is no guarantee loc will have the same address. 10.4.5 makes that distinction between an address assigned by the linker and those assigned by the compiler. 2013 Stroustrup - The C++ Programming Language 4th Edition.pdf– David C. Rankin
56 mins ago
char loc is a locally declared character that is not static. The next time f() is called there is no guarantee loc will have the same address. 10.4.5 makes that distinction between an address assigned by the linker and those assigned by the compiler. 2013 Stroustrup - The C++ Programming Language 4th Edition.pdf– David C. Rankin
56 mins ago
1
1
@DavidC.Rankin it looks like your version (a pdf) is different from mine (a hard-copy). This must have been a mistake and was updated by the time your pdf was created.
– johnnyodonnell
46 mins ago
@DavidC.Rankin it looks like your version (a pdf) is different from mine (a hard-copy). This must have been a mistake and was updated by the time your pdf was created.
– johnnyodonnell
46 mins ago
2
2
Yes, I was kinda scratching my head as to where
&glob came from, but &loc was identifiable.– David C. Rankin
43 mins ago
Yes, I was kinda scratching my head as to where
&glob came from, but &loc was identifiable.– David C. Rankin
43 mins ago
|
show 2 more comments
3 Answers
3
active
oldest
votes
Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 refers to the following code:
constexpr const char* p1="asdf";
This is OK because "asdf" is stored in a fixed memory location.
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
However, loc is not in a fixed memory location. it's on the stack and will have varying locations depending on when it is called.
answered 52 mins ago
dougdoug
8621410
So, you're saying that Bjarne should not have said that&locwill be "OK", right?
– johnnyodonnell
50 mins ago
The example code I used in the question is taken verbatim. After looking at @doug's pdf, I think the hard-copy book that I own is incorrect. I think this mistake was updated in later versions.
– johnnyodonnell
44 mins ago
Is it the same as this? github.com/boydfd/books/blob/master/seeing/stalled/…
– jackw11111
44 mins ago
@jackw11111 my version is different from the pdf provided in that link. doug provided a link to the same pdf. My hard-copy and that pdf show different examples for section 10.4.5
– johnnyodonnell
42 mins ago
add a comment |
It appears that the example from section 10.4.5 provided in my hard-copy of the "The C++ Programming Language (4th Edition)" is incorrect. And so I've concluded that the address of a local variable is not a constexpr.
The example appears to have been updated in some pdf versions as seen here:
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
add a comment |
Just to add to other answers that have pointed out the mistake, C++ standard only allows constexpr pointers to objects of static-storage duration, one past the end of such, or nullptr. See [expr.const/8] specifically #8.2;
It's worth noting that:
string-literals have static-storage duration:- Based on constraints in declaring
externvariables, they'll inherently have static-storage duration or thread local-storage duration.
Hence this is valid:
#include <string>
extern char glob;
std::string boom = "Haha";
void f(char loc) {
constexpr const char* p1 = &glob;
constexpr std::string* p2 = nullptr;
constexpr std::string* p3 = &boom;
}
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f55698844%2fis-the-address-of-a-local-variable-a-constexpr%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 refers to the following code:
constexpr const char* p1="asdf";
This is OK because "asdf" is stored in a fixed memory location.
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
However, loc is not in a fixed memory location. it's on the stack and will have varying locations depending on when it is called.
answered 52 mins ago
dougdoug
8621410
So, you're saying that Bjarne should not have said that&locwill be "OK", right?
– johnnyodonnell
50 mins ago
The example code I used in the question is taken verbatim. After looking at @doug's pdf, I think the hard-copy book that I own is incorrect. I think this mistake was updated in later versions.
– johnnyodonnell
44 mins ago
Is it the same as this? github.com/boydfd/books/blob/master/seeing/stalled/…
– jackw11111
44 mins ago
@jackw11111 my version is different from the pdf provided in that link. doug provided a link to the same pdf. My hard-copy and that pdf show different examples for section 10.4.5
– johnnyodonnell
42 mins ago
add a comment |
Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 refers to the following code:
constexpr const char* p1="asdf";
This is OK because "asdf" is stored in a fixed memory location.
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
However, loc is not in a fixed memory location. it's on the stack and will have varying locations depending on when it is called.
answered 52 mins ago
dougdoug
8621410
So, you're saying that Bjarne should not have said that&locwill be "OK", right?
– johnnyodonnell
50 mins ago
The example code I used in the question is taken verbatim. After looking at @doug's pdf, I think the hard-copy book that I own is incorrect. I think this mistake was updated in later versions.
– johnnyodonnell
44 mins ago
Is it the same as this? github.com/boydfd/books/blob/master/seeing/stalled/…
– jackw11111
44 mins ago
@jackw11111 my version is different from the pdf provided in that link. doug provided a link to the same pdf. My hard-copy and that pdf show different examples for section 10.4.5
– johnnyodonnell
42 mins ago
add a comment |
Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 refers to the following code:
constexpr const char* p1="asdf";
This is OK because "asdf" is stored in a fixed memory location.
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
However, loc is not in a fixed memory location. it's on the stack and will have varying locations depending on when it is called.
answered 52 mins ago
dougdoug
8621410
Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 refers to the following code:
constexpr const char* p1="asdf";
This is OK because "asdf" is stored in a fixed memory location.
void f(char loc) {
constexpr const char* p0 = &glob; // OK: &glob's is a constant
constexpr const char* p2 = &loc; // OK: &loc is constant in its scope
}
However, loc is not in a fixed memory location. it's on the stack and will have varying locations depending on when it is called.
answered 52 mins ago
dougdoug
8621410
answered 52 mins ago
dougdoug
8621410
answered 52 mins ago
dougdoug
8621410
answered 52 mins ago
dougdoug
8621410
8621410
So, you're saying that Bjarne should not have said that&locwill be "OK", right?
– johnnyodonnell
50 mins ago
The example code I used in the question is taken verbatim. After looking at @doug's pdf, I think the hard-copy book that I own is incorrect. I think this mistake was updated in later versions.
– johnnyodonnell
44 mins ago
Is it the same as this? github.com/boydfd/books/blob/master/seeing/stalled/…
– jackw11111
44 mins ago
@jackw11111 my version is different from the pdf provided in that link. doug provided a link to the same pdf. My hard-copy and that pdf show different examples for section 10.4.5
– johnnyodonnell
42 mins ago
add a comment |
So, you're saying that Bjarne should not have said that&locwill be "OK", right?
– johnnyodonnell
50 mins ago
The example code I used in the question is taken verbatim. After looking at @doug's pdf, I think the hard-copy book that I own is incorrect. I think this mistake was updated in later versions.
– johnnyodonnell
44 mins ago
Is it the same as this? github.com/boydfd/books/blob/master/seeing/stalled/…
– jackw11111
44 mins ago
@jackw11111 my version is different from the pdf provided in that link. doug provided a link to the same pdf. My hard-copy and that pdf show different examples for section 10.4.5
– johnnyodonnell
42 mins ago
So, you're saying that Bjarne should not have said that
&loc will be "OK", right?– johnnyodonnell
50 mins ago
So, you're saying that Bjarne should not have said that
&loc will be "OK", right?– johnnyodonnell
50 mins ago
The example code I used in the question is taken verbatim. After looking at @doug's pdf, I think the hard-copy book that I own is incorrect. I think this mistake was updated in later versions.
– johnnyodonnell
44 mins ago
The example code I used in the question is taken verbatim. After looking at @doug's pdf, I think the hard-copy book that I own is incorrect. I think this mistake was updated in later versions.
– johnnyodonnell
44 mins ago
Is it the same as this? github.com/boydfd/books/blob/master/seeing/stalled/…
– jackw11111
44 mins ago
Is it the same as this? github.com/boydfd/books/blob/master/seeing/stalled/…
– jackw11111
44 mins ago
@jackw11111 my version is different from the pdf provided in that link. doug provided a link to the same pdf. My hard-copy and that pdf show different examples for section 10.4.5
– johnnyodonnell
42 mins ago
@jackw11111 my version is different from the pdf provided in that link. doug provided a link to the same pdf. My hard-copy and that pdf show different examples for section 10.4.5
– johnnyodonnell
42 mins ago
add a comment |
It appears that the example from section 10.4.5 provided in my hard-copy of the "The C++ Programming Language (4th Edition)" is incorrect. And so I've concluded that the address of a local variable is not a constexpr.
The example appears to have been updated in some pdf versions as seen here:
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
add a comment |
It appears that the example from section 10.4.5 provided in my hard-copy of the "The C++ Programming Language (4th Edition)" is incorrect. And so I've concluded that the address of a local variable is not a constexpr.
The example appears to have been updated in some pdf versions as seen here:
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
add a comment |
It appears that the example from section 10.4.5 provided in my hard-copy of the "The C++ Programming Language (4th Edition)" is incorrect. And so I've concluded that the address of a local variable is not a constexpr.
The example appears to have been updated in some pdf versions as seen here:
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
It appears that the example from section 10.4.5 provided in my hard-copy of the "The C++ Programming Language (4th Edition)" is incorrect. And so I've concluded that the address of a local variable is not a constexpr.
The example appears to have been updated in some pdf versions as seen here:
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
answered 36 mins ago
johnnyodonnelljohnnyodonnell
378114
378114
add a comment |
add a comment |
Just to add to other answers that have pointed out the mistake, C++ standard only allows constexpr pointers to objects of static-storage duration, one past the end of such, or nullptr. See [expr.const/8] specifically #8.2;
It's worth noting that:
string-literals have static-storage duration:- Based on constraints in declaring
externvariables, they'll inherently have static-storage duration or thread local-storage duration.
Hence this is valid:
#include <string>
extern char glob;
std::string boom = "Haha";
void f(char loc) {
constexpr const char* p1 = &glob;
constexpr std::string* p2 = nullptr;
constexpr std::string* p3 = &boom;
}
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
add a comment |
Just to add to other answers that have pointed out the mistake, C++ standard only allows constexpr pointers to objects of static-storage duration, one past the end of such, or nullptr. See [expr.const/8] specifically #8.2;
It's worth noting that:
string-literals have static-storage duration:- Based on constraints in declaring
externvariables, they'll inherently have static-storage duration or thread local-storage duration.
Hence this is valid:
#include <string>
extern char glob;
std::string boom = "Haha";
void f(char loc) {
constexpr const char* p1 = &glob;
constexpr std::string* p2 = nullptr;
constexpr std::string* p3 = &boom;
}
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
add a comment |
Just to add to other answers that have pointed out the mistake, C++ standard only allows constexpr pointers to objects of static-storage duration, one past the end of such, or nullptr. See [expr.const/8] specifically #8.2;
It's worth noting that:
string-literals have static-storage duration:- Based on constraints in declaring
externvariables, they'll inherently have static-storage duration or thread local-storage duration.
Hence this is valid:
#include <string>
extern char glob;
std::string boom = "Haha";
void f(char loc) {
constexpr const char* p1 = &glob;
constexpr std::string* p2 = nullptr;
constexpr std::string* p3 = &boom;
}
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
Just to add to other answers that have pointed out the mistake, C++ standard only allows constexpr pointers to objects of static-storage duration, one past the end of such, or nullptr. See [expr.const/8] specifically #8.2;
It's worth noting that:
string-literals have static-storage duration:- Based on constraints in declaring
externvariables, they'll inherently have static-storage duration or thread local-storage duration.
Hence this is valid:
#include <string>
extern char glob;
std::string boom = "Haha";
void f(char loc) {
constexpr const char* p1 = &glob;
constexpr std::string* p2 = nullptr;
constexpr std::string* p3 = &boom;
}
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
answered 20 mins ago
WhiZTiMWhiZTiM
18.1k33153
18.1k33153
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f55698844%2fis-the-address-of-a-local-variable-a-constexpr%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
2
Clearly, &loc can't be a constexpr. However, these lines of code don't appear on my kindle version. He does show a constexpr for the address of a "C" style string in a local function. That's legal since these are in global space while loc is an argument on the stack and not constant. Is that example what you are referring to?
– doug
1 hour ago
@doug check section 10.4.5 Address Constant Expressions. I'll update the question to make this more clear. Also, my example is abridged
– johnnyodonnell
57 mins ago
2
char locis a locally declared character that is not static. The next timef()is called there is no guaranteelocwill have the same address. 10.4.5 makes that distinction between an address assigned by the linker and those assigned by the compiler. 2013 Stroustrup - The C++ Programming Language 4th Edition.pdf– David C. Rankin
56 mins ago
1
@DavidC.Rankin it looks like your version (a pdf) is different from mine (a hard-copy). This must have been a mistake and was updated by the time your pdf was created.
– johnnyodonnell
46 mins ago
2
Yes, I was kinda scratching my head as to where
&globcame from, but&locwas identifiable.– David C. Rankin
43 mins ago