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colin-home merged 1 commit into from
Sep 9, 2018
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Update compiler-warning-level-1-c4627.md #418

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29 changes: 23 additions & 6 deletions docs/error-messages/compiler-warnings/compiler-warning-level-1-c4627.md
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
---
title: "Compiler Warning (level 1) C4627 | Microsoft Docs"
ms.custom: ""
ms.date: "11/04/2016"
ms.date: "09/09/2018"
ms.technology: ["cpp-diagnostics"]
ms.topic: "error-reference"
f1_keywords: ["C4627"]
Expand All @@ -13,9 +13,26 @@ ms.author: "corob"
ms.workload: ["cplusplus"]
---
# Compiler Warning (level 1) C4627
'\<identifier>': skipped when looking for precompiled header use

> '*header_file*': skipped when looking for precompiled header use

If the current source file has the [/Yu \(Use precompiled header file)](../../build/reference/yu-use-precompiled-header-file.md) option set, then the compiler ignores everything in the file before the precompiled header is included. Warning **C4627** is generated in Visual Studio 2015 and earlier versions if *header_file* is included before the precompiled header file, and if the precompiled header does not also include *header_file*.

## Example

This sample demonstrates how the error can occur, and shows how to fix it:

```cpp
// c4627.cpp
#include <iostream> // C4627 - iostream not included by pch.h
#include "pch.h" // precompiled header file that does not include iostream
// #include <iostream> // To fix, move the iostream header include here from above
int main()
{
std::cout << "std::cout is defined!\n";
}
```

While searching for the location where a precompiled header is used, the compiler encountered an `#include` directive for the *\<identifier>* include file. The compiler ignores the `#include` directive, but issues warning **C4627** if the precompiled header does not already contain the *\<identifier>* include file.

## See Also
[Creating Precompiled Header Files](../../build/reference/creating-precompiled-header-files.md)
## See Also

[Creating Precompiled Header Files](../../build/reference/creating-precompiled-header-files.md)