how to do initialization in range-based for loop
I'm trying to use indexes in range-based for loop, so I created code as follow. I refer to this website http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0614r0.html
#include <vector>
int main(void)
std::vector<double> vector1(100);
for (std::size_t _index = 0; auto& _value : vector1)
_value = 10 + 5; //This code is for test.
++_index;
return 0;
However, it gives me several error messages (cannot deduce type of auto, cannot use uninitialized _value, etc. / Sorry, my language is not English and so are the error messages)
Why does this happen? When I use if statement with initialization like this,
if (bool is_valid = false; is_valid)
//do something
it worked just as fine.
c++ for-loop foreach compiler-errors
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
add a comment |
I'm trying to use indexes in range-based for loop, so I created code as follow. I refer to this website http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0614r0.html
#include <vector>
int main(void)
std::vector<double> vector1(100);
for (std::size_t _index = 0; auto& _value : vector1)
_value = 10 + 5; //This code is for test.
++_index;
return 0;
However, it gives me several error messages (cannot deduce type of auto, cannot use uninitialized _value, etc. / Sorry, my language is not English and so are the error messages)
Why does this happen? When I use if statement with initialization like this,
if (bool is_valid = false; is_valid)
//do something
it worked just as fine.
c++ for-loop foreach compiler-errors
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
1
The document you linked is a proposal for a future change in the standard. I am not aware of any compiler currently allowing that syntax.
– Swordfish
Nov 13 '18 at 16:06
1
Initialization in range-for is supposedly coming in future C++20 standard..
– Some programmer dude
Nov 13 '18 at 16:06
Where did you get C++20- conformant compiler?
– SergeyA
Nov 13 '18 at 16:07
1
@SergeyA Back alley. From an old guy with a flying Delorean.
– user4581301
Nov 13 '18 at 16:13
@user4581301 sharing would be caring :'(
– Swordfish
Nov 13 '18 at 16:15
add a comment |
I'm trying to use indexes in range-based for loop, so I created code as follow. I refer to this website http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0614r0.html
#include <vector>
int main(void)
std::vector<double> vector1(100);
for (std::size_t _index = 0; auto& _value : vector1)
_value = 10 + 5; //This code is for test.
++_index;
return 0;
However, it gives me several error messages (cannot deduce type of auto, cannot use uninitialized _value, etc. / Sorry, my language is not English and so are the error messages)
Why does this happen? When I use if statement with initialization like this,
if (bool is_valid = false; is_valid)
//do something
it worked just as fine.
c++ for-loop foreach compiler-errors
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
I'm trying to use indexes in range-based for loop, so I created code as follow. I refer to this website http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0614r0.html
#include <vector>
int main(void)
std::vector<double> vector1(100);
for (std::size_t _index = 0; auto& _value : vector1)
_value = 10 + 5; //This code is for test.
++_index;
return 0;
However, it gives me several error messages (cannot deduce type of auto, cannot use uninitialized _value, etc. / Sorry, my language is not English and so are the error messages)
Why does this happen? When I use if statement with initialization like this,
if (bool is_valid = false; is_valid)
//do something
it worked just as fine.
c++ for-loop foreach compiler-errors
c++ for-loop foreach compiler-errors
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
asked Nov 13 '18 at 16:03
Gi Hun NamGi Hun Nam
75
75
1
The document you linked is a proposal for a future change in the standard. I am not aware of any compiler currently allowing that syntax.
– Swordfish
Nov 13 '18 at 16:06
1
Initialization in range-for is supposedly coming in future C++20 standard..
– Some programmer dude
Nov 13 '18 at 16:06
Where did you get C++20- conformant compiler?
– SergeyA
Nov 13 '18 at 16:07
1
@SergeyA Back alley. From an old guy with a flying Delorean.
– user4581301
Nov 13 '18 at 16:13
@user4581301 sharing would be caring :'(
– Swordfish
Nov 13 '18 at 16:15
add a comment |
1
The document you linked is a proposal for a future change in the standard. I am not aware of any compiler currently allowing that syntax.
– Swordfish
Nov 13 '18 at 16:06
1
Initialization in range-for is supposedly coming in future C++20 standard..
– Some programmer dude
Nov 13 '18 at 16:06
Where did you get C++20- conformant compiler?
– SergeyA
Nov 13 '18 at 16:07
1
@SergeyA Back alley. From an old guy with a flying Delorean.
– user4581301
Nov 13 '18 at 16:13
@user4581301 sharing would be caring :'(
– Swordfish
Nov 13 '18 at 16:15
1
1
The document you linked is a proposal for a future change in the standard. I am not aware of any compiler currently allowing that syntax.
– Swordfish
Nov 13 '18 at 16:06
The document you linked is a proposal for a future change in the standard. I am not aware of any compiler currently allowing that syntax.
– Swordfish
Nov 13 '18 at 16:06
1
1
Initialization in range-for is supposedly coming in future C++20 standard..
– Some programmer dude
Nov 13 '18 at 16:06
Initialization in range-for is supposedly coming in future C++20 standard..
– Some programmer dude
Nov 13 '18 at 16:06
Where did you get C++20- conformant compiler?
– SergeyA
Nov 13 '18 at 16:07
Where did you get C++20- conformant compiler?
– SergeyA
Nov 13 '18 at 16:07
1
1
@SergeyA Back alley. From an old guy with a flying Delorean.
– user4581301
Nov 13 '18 at 16:13
@SergeyA Back alley. From an old guy with a flying Delorean.
– user4581301
Nov 13 '18 at 16:13
@user4581301 sharing would be caring :'(
– Swordfish
Nov 13 '18 at 16:15
@user4581301 sharing would be caring :'(
– Swordfish
Nov 13 '18 at 16:15
add a comment |
1 Answer
1
active
oldest
votes
This syntax is supposedly part of upcoming C++20 standard, see https://en.cppreference.com/w/cpp/language/range-for
There are currently no C++20-conformant compilers, so it is no wonder you are getting compilation errors.
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
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%2f53284939%2fhow-to-do-initialization-in-range-based-for-loop%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
This syntax is supposedly part of upcoming C++20 standard, see https://en.cppreference.com/w/cpp/language/range-for
There are currently no C++20-conformant compilers, so it is no wonder you are getting compilation errors.
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
add a comment |
This syntax is supposedly part of upcoming C++20 standard, see https://en.cppreference.com/w/cpp/language/range-for
There are currently no C++20-conformant compilers, so it is no wonder you are getting compilation errors.
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
add a comment |
This syntax is supposedly part of upcoming C++20 standard, see https://en.cppreference.com/w/cpp/language/range-for
There are currently no C++20-conformant compilers, so it is no wonder you are getting compilation errors.
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
This syntax is supposedly part of upcoming C++20 standard, see https://en.cppreference.com/w/cpp/language/range-for
There are currently no C++20-conformant compilers, so it is no wonder you are getting compilation errors.
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
answered Nov 13 '18 at 16:08
SergeyASergeyA
44.6k53990
44.6k53990
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%2f53284939%2fhow-to-do-initialization-in-range-based-for-loop%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
1
The document you linked is a proposal for a future change in the standard. I am not aware of any compiler currently allowing that syntax.
– Swordfish
Nov 13 '18 at 16:06
1
Initialization in range-for is supposedly coming in future C++20 standard..
– Some programmer dude
Nov 13 '18 at 16:06
Where did you get C++20- conformant compiler?
– SergeyA
Nov 13 '18 at 16:07
1
@SergeyA Back alley. From an old guy with a flying Delorean.
– user4581301
Nov 13 '18 at 16:13
@user4581301 sharing would be caring :'(
– Swordfish
Nov 13 '18 at 16:15