| title | auto Keyword | Microsoft Docs | |
|---|---|---|
| ms.custom | ||
| ms.date | 11/04/2016 | |
| ms.technology |
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| ms.topic | language-reference | |
| dev_langs |
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| ms.assetid | 744a41c0-2510-4140-a1be-96257e722908 | |
| author | mikeblome | |
| ms.author | mblome | |
| ms.workload |
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The auto keyword is a declaration specifier. However, the C++ standard defines an original and a revised meaning for this keyword. Before Visual C++ 2010, the auto keyword declares a variable in the automatic storage class; that is, a variable that has a local lifetime. Starting with Visual C++ 2010, the auto keyword declares a variable whose type is deduced from the initialization expression in its declaration. The /Zc:auto[-] compiler option controls the meaning of the auto keyword.
auto declarator ;
auto declarator initializer; The definition of the auto keyword changes in the C++ programming language, but not in the C programming language.
The following topics describe the auto keyword and the corresponding compiler option:
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auto describes the new definition of the auto keyword.
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/Zc:auto (Deduce Variable Type) describes the compiler option that tells the compiler which definition of the auto keyword to use.