用C默认构造函数 [英] Default constructor in C

问题描述

有没有一种方法有某种默认构造函数（如C ++的）与结构定义的C用户类型？

我已经有一个宏它就像一个快速初始化（如一个 pthread_mutex ），但我想知道，如果你可以通过任何机会，有部分（或全部在填写申报一个结构的）领域。

例如，用 pthread_mutex 的例子，我想

  pthread_mutex_t my_mutex;
 

有尽可能

同样的效果

  pthread_mutex_t my_mutex = PTHREAD_MUTEX_INITIALIZER;
 

解决方案

您可以创建一个指针指向的结构初始化功能。这是常见的做法。

此外，创造一个结构和初始化函数（如工厂） - 所以从来没有一个时间，其中的结构是初始化中的客户code。当然 - 假定人们按照惯例，使用构造/工厂...

可怕的伪code上的malloc或免费的没有错误检查

  somestruct * somestruct_factory（/ *每个HAPS一些初始化AGRS？* /）
{
  MALLOC一些东西
  填写一些东西
  返回指针malloced东西
}
无效somestruct_destructor（somestruct *）
{
  做清理的东西，也是免费的指针
  免费（somestruct）;
}
 

有人可能会一起去，并解释如何一些C ++初preprocessors /编译器的工作做这一切的温度。

Is there a way to have some kind of default constructor (like a C++ one) for C user types defined with a structure?

I already have a macro which works like a fast initializer (like the one for pthread_mutex) but I wanted to know if you can by any chance have some (or all) fields of a struct filled at declaration.

For instance, with the pthread_mutex example, I would like

pthread_mutex_t my_mutex;

to have the same effect as

pthread_mutex_t my_mutex = PTHREAD_MUTEX_INITIALIZER;

解决方案

You can create initializer functions that take a pointer to a structure. This was common practice.

Also functions that create a struct and initialize it (like a factory) - so there is never a time where the struct is "uninitialized" in the "client" code. Of course - that assumes people follow the convention and use the "constructor"/factory...

horrible pseudo code with NO error checking on malloc or free

somestruct* somestruct_factory(/* per haps some initializer agrs? */)
{
  malloc some stuff
  fill in some stuff
  return pointer to malloced stuff
}


void somestruct_destructor(somestruct*)
{
  do cleanup stuff and also free pointer
  free(somestruct);
}

Someone will probably come along and explain how some early C++ preprocessors/compilers worked to do this all in C.

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