{"id":13536,"date":"2022-10-04T10:02:05","date_gmt":"2022-10-04T04:32:05","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-why-not-have-all-variables-be-a-constexpr-closed\/"},"modified":"2022-10-04T10:02:05","modified_gmt":"2022-10-04T04:32:05","slug":"solved-why-not-have-all-variables-be-a-constexpr-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-why-not-have-all-variables-be-a-constexpr-closed\/","title":{"rendered":"[Solved] Why not have all variables be a constexpr? [closed]"},"content":{"rendered":"

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First of all not all variables can be made constexpr<\/code>. For example<\/p>\n

int x;\nstd::cin >> x;\n<\/code><\/pre>\n
Obviously x<\/code> cannot be constexpr<\/code>. The value it will have after it has been read from input is not a compile-time constant.<\/p>\n
Second, constexpr<\/code> is part of the contract of a variable or function. By marking it constexpr<\/code>, you allow other code to use it in a context that requires a constant expression. That means even if it might be possible to declare it constexpr<\/code> now, you should not do so if you are planning on potentially changing the code so that it will not be constexpr<\/code> later. If you were to mark it constexpr<\/code> now, other code might come to rely on this property, and that code will stop compiling when constexpr<\/code> is removed in a future version of the program.<\/p>\n<\/p><\/div>\n
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solved Why not have all variables be a constexpr? [closed] <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] First of all not all variables can be made constexpr. For example int x; std::cin >> x; Obviously x cannot be constexpr. The value it will have after it has been read from input is not a compile-time constant. Second, constexpr is part of the contract of a variable or function. By marking it … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[324],"class_list":["post-13536","post","type-post","status-publish","format-standard","hentry","category-solved","tag-c"],"yoast_head":"\n[Solved] Why not have all variables be a constexpr? [closed] - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-why-not-have-all-variables-be-a-constexpr-closed\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Why not have all variables be a constexpr? [closed] - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] First of all not all variables can be made constexpr. For example int x; std::cin >> x; Obviously x cannot be constexpr. The value it will have after it has been read from input is not a compile-time constant. Second, constexpr is part of the contract of a variable or function. By marking it ... 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