保留errno的值 [英] Preserving the value of errno

问题描述

假设我正在编写一个函数，如果出现问题，将设置

errno的值但是我还要

想要保证errno将保留如果函数成功完成任务，则
不变。所以在

我的代码的开头我有类似

int errsto = errno;

并且在每次成功返回之前我都有

errno = errsto;


这样可以吗？

解决方案

Spiros Bousbouras写道：

假设我正在编写一个函数，如果出现问题，将设置

errno的值但是我还要

想要保证errno保持不变

如果该功能成功完成了它的任务。所以在

我的代码的开头我有类似

int errsto = errno;

并且在每次成功返回之前我都有

errno = errsto;


这样可以吗？

为什么不把errno设置为你的错误什么东西回来之前

出错？

-

Pietro Cerutti


PGP公钥：
http://gahr.ch/pgp

Pietro Cerutti写道：

Spiros Bousbouras写道：

> ;假设我正在编写一个函数，如果出现问题，将设置errno的值但是我还要保证errno将保持不变
如果函数完成了任务成功。所以，在我的代码的开头，我有类似的东西，比如
int errsto = errno;
在每次成功返回之前我都有
errno = errsto;

这样可以吗？

为什么不在错误之前将errno设置为你的错误

出错？

!!!!!


非常好的答案。

Pietro Cerutti写道：

Spiros Bousbouras写道：

>>假设我是编写一个函数，如果出现问题，将设置errno的值但是我还要保证errno将保持不变
如果函数成功完成其任务。所以，在我的代码的开头，我有类似的东西，比如
int errsto = errno;
在每次成功返回之前我都有
errno = errsto;

这样可以吗？

为什么不在错误之前将errno设置为你的错误

出错？

我以为他想防止它被任何功能改变

他又轮流打电话......

Assume I''m writing a function which is going to set
the value of errno if something went wrong but I also
want to guarantee that errno will remain unchanged
if the function completed its task succesfully. So at
the beginning of my code I have something like
int errsto = errno ;
and just before every successful return I have
errno = errsto ;

Is this ok ?

解决方案

Spiros Bousbouras wrote:

Assume I''m writing a function which is going to set
the value of errno if something went wrong but I also
want to guarantee that errno will remain unchanged
if the function completed its task succesfully. So at
the beginning of my code I have something like
int errsto = errno ;
and just before every successful return I have
errno = errsto ;

Is this ok ?

Why not just set errno to your error before returning when something
goes wrong?
--
Pietro Cerutti

PGP Public Key:
http://gahr.ch/pgp

Pietro Cerutti wrote:

Spiros Bousbouras wrote:

>Assume I''m writing a function which is going to set
the value of errno if something went wrong but I also
want to guarantee that errno will remain unchanged
if the function completed its task succesfully. So at
the beginning of my code I have something like
int errsto = errno ;
and just before every successful return I have
errno = errsto ;

Is this ok ?

Why not just set errno to your error before returning when something
goes wrong?

!!!!!

Very good answer.

Pietro Cerutti wrote:

Spiros Bousbouras wrote:

>>Assume I''m writing a function which is going to set
the value of errno if something went wrong but I also
want to guarantee that errno will remain unchanged
if the function completed its task succesfully. So at
the beginning of my code I have something like
int errsto = errno ;
and just before every successful return I have
errno = errsto ;

Is this ok ?

Why not just set errno to your error before returning when something
goes wrong?

I assumed he wanted to guard against it being changed by any functions
he called in turn...

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