Why can std:set (with a single colon) compile?
I accidentally wrote
std::set<string> keys;
as:
std:set<string> keys;
but weirdly enough, Visual Studio 2013 still compiles.
Why does this happen?
Actually keys is not only defined, but later used as a set of strings, such as
if(keys.find(keystr)==keys.end())
keys.insert(keystr);
toret.push_back(tempv);
c++ visual-studio
edited Aug 28 '18 at 9:13
numbermaniac
63011427
asked Aug 28 '18 at 3:01
athosathos
2,21913166
add a comment |
I accidentally wrote
std::set<string> keys;
as:
std:set<string> keys;
but weirdly enough, Visual Studio 2013 still compiles.
Why does this happen?
Actually keys is not only defined, but later used as a set of strings, such as
if(keys.find(keystr)==keys.end())
keys.insert(keystr);
toret.push_back(tempv);
c++ visual-studio
edited Aug 28 '18 at 9:13
numbermaniac
63011427
asked Aug 28 '18 at 3:01
athosathos
2,21913166
12
std:is interpreted as alabelfor agoto. see: en.cppreference.com/w/cpp/language/goto
– Sandburg
Aug 28 '18 at 7:05
10
To those voting to close this thing, OP has identified the typo and wants to understand why it does what it does.
– Joshua
Aug 28 '18 at 16:06
5
Stop close-voting this, people. It's on-topic. We will just reopen it immediately.
– smci
Aug 29 '18 at 0:40
1
@smci While I agree that this question should stay open, it's not really your place to tell people how to use their votes. Let them use theirs, and you use yours.
– Jonathon Reinhart
Aug 29 '18 at 0:50
2
@JonathonReinhart: there's no dispute that it isn't on-topic, is there? Noone has suggested any reason why.
– smci
Aug 29 '18 at 1:41
add a comment |
I accidentally wrote
std::set<string> keys;
as:
std:set<string> keys;
but weirdly enough, Visual Studio 2013 still compiles.
Why does this happen?
Actually keys is not only defined, but later used as a set of strings, such as
if(keys.find(keystr)==keys.end())
keys.insert(keystr);
toret.push_back(tempv);
c++ visual-studio
edited Aug 28 '18 at 9:13
numbermaniac
63011427
asked Aug 28 '18 at 3:01
athosathos
2,21913166
I accidentally wrote
std::set<string> keys;
as:
std:set<string> keys;
but weirdly enough, Visual Studio 2013 still compiles.
Why does this happen?
Actually keys is not only defined, but later used as a set of strings, such as
if(keys.find(keystr)==keys.end())
keys.insert(keystr);
toret.push_back(tempv);
c++ visual-studio
c++ visual-studio
edited Aug 28 '18 at 9:13
numbermaniac
63011427
asked Aug 28 '18 at 3:01
athosathos
2,21913166
edited Aug 28 '18 at 9:13
numbermaniac
63011427
asked Aug 28 '18 at 3:01
athosathos
2,21913166
edited Aug 28 '18 at 9:13
numbermaniac
63011427
edited Aug 28 '18 at 9:13
numbermaniac
63011427
edited Aug 28 '18 at 9:13
numbermaniac
63011427
63011427
asked Aug 28 '18 at 3:01
athosathos
2,21913166
asked Aug 28 '18 at 3:01
athosathos
2,21913166
asked Aug 28 '18 at 3:01
athosathos
2,21913166
2,21913166
12
std:is interpreted as alabelfor agoto. see: en.cppreference.com/w/cpp/language/goto
– Sandburg
Aug 28 '18 at 7:05
10
To those voting to close this thing, OP has identified the typo and wants to understand why it does what it does.
– Joshua
Aug 28 '18 at 16:06
5
Stop close-voting this, people. It's on-topic. We will just reopen it immediately.
– smci
Aug 29 '18 at 0:40
1
@smci While I agree that this question should stay open, it's not really your place to tell people how to use their votes. Let them use theirs, and you use yours.
– Jonathon Reinhart
Aug 29 '18 at 0:50
2
@JonathonReinhart: there's no dispute that it isn't on-topic, is there? Noone has suggested any reason why.
– smci
Aug 29 '18 at 1:41
add a comment |
12
std:is interpreted as alabelfor agoto. see: en.cppreference.com/w/cpp/language/goto
– Sandburg
Aug 28 '18 at 7:05
10
To those voting to close this thing, OP has identified the typo and wants to understand why it does what it does.
– Joshua
Aug 28 '18 at 16:06
5
Stop close-voting this, people. It's on-topic. We will just reopen it immediately.
– smci
Aug 29 '18 at 0:40
1
@smci While I agree that this question should stay open, it's not really your place to tell people how to use their votes. Let them use theirs, and you use yours.
– Jonathon Reinhart
Aug 29 '18 at 0:50
2
@JonathonReinhart: there's no dispute that it isn't on-topic, is there? Noone has suggested any reason why.
– smci
Aug 29 '18 at 1:41
12
12
std: is interpreted as a label for a goto. see: en.cppreference.com/w/cpp/language/goto– Sandburg
Aug 28 '18 at 7:05
std: is interpreted as a label for a goto. see: en.cppreference.com/w/cpp/language/goto– Sandburg
Aug 28 '18 at 7:05
10
10
To those voting to close this thing, OP has identified the typo and wants to understand why it does what it does.
– Joshua
Aug 28 '18 at 16:06
To those voting to close this thing, OP has identified the typo and wants to understand why it does what it does.
– Joshua
Aug 28 '18 at 16:06
5
5
Stop close-voting this, people. It's on-topic. We will just reopen it immediately.
– smci
Aug 29 '18 at 0:40
Stop close-voting this, people. It's on-topic. We will just reopen it immediately.
– smci
Aug 29 '18 at 0:40
1
1
@smci While I agree that this question should stay open, it's not really your place to tell people how to use their votes. Let them use theirs, and you use yours.
– Jonathon Reinhart
Aug 29 '18 at 0:50
@smci While I agree that this question should stay open, it's not really your place to tell people how to use their votes. Let them use theirs, and you use yours.
– Jonathon Reinhart
Aug 29 '18 at 0:50
2
2
@JonathonReinhart: there's no dispute that it isn't on-topic, is there? Noone has suggested any reason why.
– smci
Aug 29 '18 at 1:41
@JonathonReinhart: there's no dispute that it isn't on-topic, is there? Noone has suggested any reason why.
– smci
Aug 29 '18 at 1:41
add a comment |
2 Answers
2
active
oldest
votes
At block scope, an identifier followed by a single colon introduces a label. Thus, your statement is equivalent to:
set<string> keys;
except that it bears the label std and can be jumped to by the statement goto std;.
For some reason, the name set is known to the compiler---perhaps you did using namespace std;, or using std::set;, or something like that, or perhaps you defined your own set type somewhere.
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
42
This is another reason to avoidusing namespace std;andusing std::set;
– R Sahu
Aug 28 '18 at 3:40
32
There are good arguments to be made againstusing namespace std/using std::set, but I'm not sure this is one of them... the main argument is usually that namespaces are there to prevent collisions, but if there is a non-std 'set' to collide with, thenstd: set<...>would probably be valid. Common practice is to limit any such using declarations to another namespace/function, but this problem could just as easily happen in that scope. I would sooner expect a typo to creep in rewritingstd::chrono::high_resolution_clock, etc. ad nauseum than this label typo (the first I've seen like it.)
– John P
Aug 28 '18 at 11:50
add a comment |
In the second case, std is a label. It is the same as spelling default incorrectly in a case statement.
answered Aug 28 '18 at 3:04
cupcup
4,71221026
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
At block scope, an identifier followed by a single colon introduces a label. Thus, your statement is equivalent to:
set<string> keys;
except that it bears the label std and can be jumped to by the statement goto std;.
For some reason, the name set is known to the compiler---perhaps you did using namespace std;, or using std::set;, or something like that, or perhaps you defined your own set type somewhere.
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
42
This is another reason to avoidusing namespace std;andusing std::set;
– R Sahu
Aug 28 '18 at 3:40
32
There are good arguments to be made againstusing namespace std/using std::set, but I'm not sure this is one of them... the main argument is usually that namespaces are there to prevent collisions, but if there is a non-std 'set' to collide with, thenstd: set<...>would probably be valid. Common practice is to limit any such using declarations to another namespace/function, but this problem could just as easily happen in that scope. I would sooner expect a typo to creep in rewritingstd::chrono::high_resolution_clock, etc. ad nauseum than this label typo (the first I've seen like it.)
– John P
Aug 28 '18 at 11:50
add a comment |
At block scope, an identifier followed by a single colon introduces a label. Thus, your statement is equivalent to:
set<string> keys;
except that it bears the label std and can be jumped to by the statement goto std;.
For some reason, the name set is known to the compiler---perhaps you did using namespace std;, or using std::set;, or something like that, or perhaps you defined your own set type somewhere.
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
42
This is another reason to avoidusing namespace std;andusing std::set;
– R Sahu
Aug 28 '18 at 3:40
32
There are good arguments to be made againstusing namespace std/using std::set, but I'm not sure this is one of them... the main argument is usually that namespaces are there to prevent collisions, but if there is a non-std 'set' to collide with, thenstd: set<...>would probably be valid. Common practice is to limit any such using declarations to another namespace/function, but this problem could just as easily happen in that scope. I would sooner expect a typo to creep in rewritingstd::chrono::high_resolution_clock, etc. ad nauseum than this label typo (the first I've seen like it.)
– John P
Aug 28 '18 at 11:50
add a comment |
At block scope, an identifier followed by a single colon introduces a label. Thus, your statement is equivalent to:
set<string> keys;
except that it bears the label std and can be jumped to by the statement goto std;.
For some reason, the name set is known to the compiler---perhaps you did using namespace std;, or using std::set;, or something like that, or perhaps you defined your own set type somewhere.
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
At block scope, an identifier followed by a single colon introduces a label. Thus, your statement is equivalent to:
set<string> keys;
except that it bears the label std and can be jumped to by the statement goto std;.
For some reason, the name set is known to the compiler---perhaps you did using namespace std;, or using std::set;, or something like that, or perhaps you defined your own set type somewhere.
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
answered Aug 28 '18 at 3:03
BrianBrian
65.7k798186
65.7k798186
42
This is another reason to avoidusing namespace std;andusing std::set;
– R Sahu
Aug 28 '18 at 3:40
32
There are good arguments to be made againstusing namespace std/using std::set, but I'm not sure this is one of them... the main argument is usually that namespaces are there to prevent collisions, but if there is a non-std 'set' to collide with, thenstd: set<...>would probably be valid. Common practice is to limit any such using declarations to another namespace/function, but this problem could just as easily happen in that scope. I would sooner expect a typo to creep in rewritingstd::chrono::high_resolution_clock, etc. ad nauseum than this label typo (the first I've seen like it.)
– John P
Aug 28 '18 at 11:50
add a comment |
42
This is another reason to avoidusing namespace std;andusing std::set;
– R Sahu
Aug 28 '18 at 3:40
32
There are good arguments to be made againstusing namespace std/using std::set, but I'm not sure this is one of them... the main argument is usually that namespaces are there to prevent collisions, but if there is a non-std 'set' to collide with, thenstd: set<...>would probably be valid. Common practice is to limit any such using declarations to another namespace/function, but this problem could just as easily happen in that scope. I would sooner expect a typo to creep in rewritingstd::chrono::high_resolution_clock, etc. ad nauseum than this label typo (the first I've seen like it.)
– John P
Aug 28 '18 at 11:50
42
42
This is another reason to avoid
using namespace std; and using std::set;– R Sahu
Aug 28 '18 at 3:40
This is another reason to avoid
using namespace std; and using std::set;– R Sahu
Aug 28 '18 at 3:40
32
32
There are good arguments to be made against
using namespace std/using std::set, but I'm not sure this is one of them... the main argument is usually that namespaces are there to prevent collisions, but if there is a non-std 'set' to collide with, then std: set<...> would probably be valid. Common practice is to limit any such using declarations to another namespace/function, but this problem could just as easily happen in that scope. I would sooner expect a typo to creep in rewriting std::chrono::high_resolution_clock, etc. ad nauseum than this label typo (the first I've seen like it.)– John P
Aug 28 '18 at 11:50
There are good arguments to be made against
using namespace std/using std::set, but I'm not sure this is one of them... the main argument is usually that namespaces are there to prevent collisions, but if there is a non-std 'set' to collide with, then std: set<...> would probably be valid. Common practice is to limit any such using declarations to another namespace/function, but this problem could just as easily happen in that scope. I would sooner expect a typo to creep in rewriting std::chrono::high_resolution_clock, etc. ad nauseum than this label typo (the first I've seen like it.)– John P
Aug 28 '18 at 11:50
add a comment |
In the second case, std is a label. It is the same as spelling default incorrectly in a case statement.
answered Aug 28 '18 at 3:04
cupcup
4,71221026
add a comment |
In the second case, std is a label. It is the same as spelling default incorrectly in a case statement.
answered Aug 28 '18 at 3:04
cupcup
4,71221026
add a comment |
In the second case, std is a label. It is the same as spelling default incorrectly in a case statement.
answered Aug 28 '18 at 3:04
cupcup
4,71221026
In the second case, std is a label. It is the same as spelling default incorrectly in a case statement.
answered Aug 28 '18 at 3:04
cupcup
4,71221026
answered Aug 28 '18 at 3:04
cupcup
4,71221026
answered Aug 28 '18 at 3:04
cupcup
4,71221026
answered Aug 28 '18 at 3:04
cupcup
4,71221026
4,71221026
add a comment |
add a comment |
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12
std:is interpreted as alabelfor agoto. see: en.cppreference.com/w/cpp/language/goto– Sandburg
Aug 28 '18 at 7:05
10
To those voting to close this thing, OP has identified the typo and wants to understand why it does what it does.
– Joshua
Aug 28 '18 at 16:06
5
Stop close-voting this, people. It's on-topic. We will just reopen it immediately.
– smci
Aug 29 '18 at 0:40
1
@smci While I agree that this question should stay open, it's not really your place to tell people how to use their votes. Let them use theirs, and you use yours.
– Jonathon Reinhart
Aug 29 '18 at 0:50
2
@JonathonReinhart: there's no dispute that it isn't on-topic, is there? Noone has suggested any reason why.
– smci
Aug 29 '18 at 1:41