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colin-home merged 2 commits into from
Apr 19, 2022
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Repo sync for protected CLA branch #3842

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0fe4576
4/19/2022 AM Publish (#4233)
Taojunshen Apr 19, 2022
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Merging changes synced from https://github.com/MicrosoftDocs/cpp-docs…
opbld17 Apr 19, 2022
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14 changes: 6 additions & 8 deletions docs/build/reference/internal-partition.md
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Original file line number Diff line number Diff line change
@@ -1,35 +1,33 @@
---
title: "/internalPartition"
description: "Use the /internalPartition compiler option to treat the input file as an internal partition unit."
ms.date: 04/15/2022
ms.date: 04/18/2022
author: "tylermsft"
ms.author: "twhitney"
f1_keywords: ["/internalPartition", "VC.Project.VCCLCompilerTool.Interface"]
helpviewer_keywords: ["/internalPartition", "Translate include directives into import directives"]
---
# `/internalPartition`

Use this switch to treat the input file on the command line as an [internal partition unit](http://eel.is/c%2B%2Bdraft/module#unit-4.3).
Use the **`/internalPartition`** compiler option to treat the input file as an *internal partition unit*, which is a [module partition implementation unit](../../cpp/modules-cpp.md#implementing-modules) that doesn't contribute to the external interface of the module.

## Syntax

> **`/internalPartition`** *`filename`*

## Remarks

The following example demonstrates using the `/internalPartition` switch:

`m-internals.cpp`:
The following example demonstrates how to use the `/internalPartition` option:

```cpp
// m-internals.cpp
module m:internals;

void internalFunc() {} // cannot have `export` since this is an internal partition
```

`m.ixx`:

```cpp
// m.ixx
export module m;
import :internals; // Cannot export this partition.

Expand All @@ -43,7 +41,7 @@ To compile this interface:
cl /std:c++latest /internalPartition /c m-internals.cpp
```

This switch can't be used with the [`/interface`](interface.md) compiler switch.
This option can't be used with the [`/interface`](interface.md) compiler option.

**`/internalPartition`** is available in Visual Studio 2019 version 16.10, or later.\
**`/internalPartition`** requires [/std:c++20](std-specify-language-standard-version.md) or later.
Expand Down
73 changes: 37 additions & 36 deletions docs/c-runtime-library/reference/matherr.md
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---
description: "Learn more about: _matherr"
title: "_matherr"
ms.date: "04/05/2018"
ms.date: "04/18/2012"
api_name: ["_matherr"]
api_location: ["msvcrt.dll", "msvcr80.dll", "msvcr90.dll", "msvcr100.dll", "msvcr100_clr0400.dll", "msvcr110.dll", "msvcr110_clr0400.dll", "msvcr120.dll", "msvcr120_clr0400.dll", "ucrtbase.dll"]
api_type: ["DLLExport"]
topic_type: ["apiref"]
f1_keywords: ["_matherr", "matherr"]
helpviewer_keywords: ["_matherr function", "matherr function"]
ms.assetid: b600d66e-165a-4608-a856-8fb418d46760
---
# _matherr
# `_matherr`

Handles math errors.

## Syntax

```C
int _matherr( struct _exception * except );
int _matherr(struct _exception *except);
```

### Parameters

*except*<br/>
*`except`*\
Pointer to the structure containing error information.

## Return Value

**_matherr** returns 0 to indicate an error, or a nonzero value to indicate success. If **_matherr** returns 0, an error message can be displayed and **errno** is set to an appropriate error value. If **_matherr** returns a nonzero value, no error message is displayed and **errno** remains unchanged.
**`_matherr`** returns 0 to indicate an error, or a nonzero value to indicate success:
- If **`_matherr`** returns 0, an error message can be displayed and **`errno`** is set to an appropriate error value.
- If **`_matherr`** returns a nonzero value, no error message is displayed and **`errno`** remains unchanged.

For more information about return codes, see [_doserrno, errno, _sys_errlist, and _sys_nerr](../../c-runtime-library/errno-doserrno-sys-errlist-and-sys-nerr.md).
For more information about return codes, see [`_doserrno`, `errno`, `_sys_errlist`, and `_sys_nerr`](../../c-runtime-library/errno-doserrno-sys-errlist-and-sys-nerr.md).

## Remarks

The **_matherr** function processes errors generated by the floating-point functions of the math library. These functions call **_matherr** when an error is detected.
The **`_matherr`** function processes errors generated by the floating-point functions of the math library. These functions call **`_matherr`** when an error is detected. This interaction isn't impacted by the [floating-point mode of the compiler](../../build/reference/fp-specify-floating-point-behavior.md) or the [floating point control word](../../c-runtime-library/reference/control87-controlfp-control87-2.md). Since **`_matherr`** is a library function, math [intrinsic functions](../../intrinsics/compiler-intrinsics.md) won't call it.

For special error handling, you can provide a different definition of **_matherr**. If you use the dynamically linked version of the C run-time library (CRT), you can replace the default **_matherr** routine in a client executable with a user-defined version. However, you cannot replace the default **_matherr** routine in a DLL client of the CRT DLL.
For special error handling, you can provide a different definition of **`_matherr`**. If you use the dynamically linked version of the C run-time library (CRT), you can replace the default **`_matherr`** routine in a client executable with a user-defined version. However, you can't replace the default **`_matherr`** routine in a DLL client of the CRT DLL.

When an error occurs in a math routine, **_matherr** is called with a pointer to an **_exception** type structure (defined in \<math.h>) as an argument. The **_exception** structure contains the following elements.
When an error occurs in a math routine, **`_matherr`** is called with a pointer to an **`_exception`** type structure (defined in `<math.h>`) as an argument. The **`_exception`** structure contains the following elements.

```C
struct _exception
Expand All @@ -50,36 +51,36 @@ struct _exception
};
```

The **type** member specifies the type of math error. It is one of the following values, defined in \<math.h>:
The **`type`** member specifies the type of math error. It's one of the following values, defined in `<math.h>`:

|Macro|Meaning|
|-|-|
| **_DOMAIN** | Argument domain error |
| **_SING** | Argument singularity |
| **_OVERFLOW** | Overflow range error |
| **_PLOSS** | Partial loss of significance |
| **_TLOSS** | Total loss of significance |
| **_UNDERFLOW** | The result is too small to be represented. (This condition is not currently supported.) |
| **`_DOMAIN`** | Argument domain error |
| **`_SING`** | Argument singularity |
| **`_OVERFLOW`** | Overflow range error |
| **`_PLOSS`** | Partial loss of significance |
| **`_TLOSS`** | Total loss of significance |
| **`_UNDERFLOW`** | The result is too small to be represented. (This condition isn't currently supported.) |

The structure member **name** is a pointer to a null-terminated string containing the name of the function that caused the error. The structure members **arg1** and **arg2** specify the values that caused the error. If only one argument is given, it is stored in **arg1**.
The structure member **`name`** is a pointer to a null-terminated string containing the name of the function that caused the error. The structure members **`arg1`** and **`arg2`** specify the values that caused the error. If only one argument is given, it's stored in **`arg1`**.

The default return value for the given error is **retval**. If you change the return value, it must specify whether an error actually occurred.
The default return value for the given error is **`retval`**. If you change the return value, it must specify whether an error actually occurred.

## Requirements

|Routine|Required header|
|-------------|---------------------|
|**_matherr**|\<math.h>|
|**`_matherr`**|`<math.h>`|

For more compatibility information, see [Compatibility](../../c-runtime-library/compatibility.md).

## Example

```C
// crt_matherr.c
/* illustrates writing an error routine for math
* functions. The error function must be:
* _matherr
/* crt_matherr.c
* Illustrates writing an error routine for math
* functions.
* The error handling function must be named _matherr
*/

#include <math.h>
Expand All @@ -102,27 +103,27 @@ int main()
* returns the natural or base-10 logarithm of the absolute value
* of the argument and suppresses the usual error message.
*/
int _matherr( struct _exception *except )
int _matherr(struct _exception *except)
{
/* Handle _DOMAIN errors for log or log10. */
if( except->type == _DOMAIN )
if (except->type == _DOMAIN)
{
if( strcmp( except->name, "log" ) == 0 )
if (strcmp(except->name, "log") == 0)
{
except->retval = log( -(except->arg1) );
printf( "Special: using absolute value: %s: _DOMAIN "
"error\n", except->name );
except->retval = log(-(except->arg1));
printf("Special: using absolute value: %s: _DOMAIN "
"error\n", except->name);
return 1;
}
else if( strcmp( except->name, "log10" ) == 0 )
else if (strcmp(except->name, "log10") == 0)
{
except->retval = log10( -(except->arg1) );
printf( "Special: using absolute value: %s: _DOMAIN "
"error\n", except->name );
except->retval = log10(-(except->arg1));
printf("Special: using absolute value: %s: _DOMAIN "
"error\n", except->name);
return 1;
}
}
printf( "Normal: " );
printf("Normal: ");
return 0; /* Else use the default actions */
}
```
Expand All @@ -137,4 +138,4 @@ Normal: log( 0.0 ) = -inf

## See also

[Floating-Point Support](../../c-runtime-library/floating-point-support.md)<br/>
[Floating-Point Support](../../c-runtime-library/floating-point-support.md)