# 字典对象

`PyDictObject`

  这个 `PyObject` 的子类型代表一个Python字典对象。

PyTypeObject `PyDict_Type`

  This instance of `PyTypeObject` represents the Python dictionary type. This is exposed to Python programs as `dict` and `types.DictType`.

int `PyDict_Check`(PyObject *p)

  如果 p 是字典对象或者字典类型的子类型的实例，则返回真。

  在 2.2 版更改: Allowed subtypes to be accepted.

int `PyDict_CheckExact`(PyObject *p)

  如果 p 是字典对象但不是字典类型的子类型的实例，则返回真。

  2.4 新版功能.

PyObject* `PyDict_New`()
  Return value: New reference.

  Return a new empty dictionary, or NULL on failure.

PyObject* `PyDictProxy_New`(PyObject *dict)
  Return value: New reference.

  Return a proxy object for a mapping which enforces read-only behavior. This is normally used to create a proxy to prevent modification of the dictionary for non-dynamic class types.

  2.2 新版功能.

void `PyDict_Clear`(PyObject *p)

  清空现有字典的所有键值对。

int `PyDict_Contains`(PyObject *p, PyObject *key)

  确定 key 是否包含在字典 p 中。如果 key 匹配上 p 的某一项，则返回 `1` ，否则返回 `0` 。返回 `-1` 表示出错。这等同于Python表达式 `key in p` 。

  2.4 新版功能.

PyObject* `PyDict_Copy`(PyObject *p)
  Return value: New reference.

  返回与 p 包含相同键值对的新字典。

  1.6 新版功能.

int `PyDict_SetItem`(PyObject *p, PyObject *key, PyObject *val)

  使用 key 作为键将 value 插入字典 p 。 key 必须为 hashable ；如果不是，会抛出 `TypeError` 异常。成功返回 `0` ，失败返回 `-1` 。

int `PyDict_SetItemString`(PyObject *p, const char *key, PyObject *val)

  Insert value into the dictionary p using key as a key. key should be a `char*`. The key object is created using `PyString_FromString(key)`. Return `0` on success or `-1` on failure.

int `PyDict_DelItem`(PyObject *p, PyObject *key)

  使用键 key 删除字典 p 中的条目。 key 必须是可哈希的；如果不是，则抛出 `TypeError` 异常。成功时返回 `0` ，失败时返回 `-1` 。

int `PyDict_DelItemString`(PyObject *p, char *key)

  删除字典 p 中由字符串 key 作为键的条目。成功时返回 `0` ，失败时返回 `-1`。

PyObject* `PyDict_GetItem`(PyObject *p, PyObject *key)
  Return value: Borrowed reference.

  Return the object from dictionary p which has a key key. Return NULL if the key key is not present, but without setting an exception.

PyObject* `PyDict_GetItemString`(PyObject *p, const char *key)
  Return value: Borrowed reference.

  This is the same as `PyDict_GetItem()`, but key is specified as a `char*`, rather than a `PyObject*`.

PyObject* `PyDict_Items`(PyObject *p)
  Return value: New reference.

  Return a `PyListObject` containing all the items from the dictionary, as in the dictionary method `dict.items()`.

PyObject* `PyDict_Keys`(PyObject *p)
  Return value: New reference.

  Return a `PyListObject` containing all the keys from the dictionary, as in the dictionary method `dict.keys()`.

PyObject* `PyDict_Values`(PyObject *p)
  Return value: New reference.

  Return a `PyListObject` containing all the values from the dictionary p, as in the dictionary method `dict.values()`.

Py_ssize_t `PyDict_Size`(PyObject *p)

  返回字典中项目数，等价于对字典 p 使用 `len(p)`。

  在 2.5 版更改: This function returned an `int` type. This might require changes in your code for properly supporting 64-bit systems.

int `PyDict_Next`(PyObject *p, Py_ssize_t *ppos, PyObject **pkey, PyObject **pvalue)

  Iterate over all key-value pairs in the dictionary p. The `Py_ssize_t` referred to by ppos must be initialized to `0` prior to the first call to this function to start the iteration; the function returns true for each pair in the dictionary, and false once all pairs have been reported. The parameters pkey and pvalue should either point to `PyObject*` variables that will be filled in with each key and value, respectively, or may be NULL. Any references returned through them are borrowed. ppos should not be altered during iteration. Its value represents offsets within the internal dictionary structure, and since the structure is sparse, the offsets are not consecutive.

  例如

      PyObject *key, *value;
      Py_ssize_t pos = 0;

      while (PyDict_Next(self->dict, &pos, &key, &value)) {
          /* do something interesting with the values... */
          ...
      }

  The dictionary p should not be mutated during iteration. It is safe (since Python 2.1) to modify the values of the keys as you iterate over the dictionary, but only so long as the set of keys does not change. For example:

      PyObject *key, *value;
      Py_ssize_t pos = 0;

      while (PyDict_Next(self->dict, &pos, &key, &value)) {
          int i = PyInt_AS_LONG(value) + 1;
          PyObject *o = PyInt_FromLong(i);
          if (o == NULL)
              return -1;
          if (PyDict_SetItem(self->dict, key, o) < 0) {
              Py_DECREF(o);
              return -1;
          }
          Py_DECREF(o);
      }

  在 2.5 版更改: This function used an `int *` type for ppos. This might require changes in your code for properly supporting 64-bit systems.

int `PyDict_Merge`(PyObject *a, PyObject *b, int override)

  对映射对象 b 进行迭代，将键值对添加到字典 a。 b 可以是一个字典，或任何支持 `PyMapping_Keys()` 和 `PyObject_GetItem()` 的对象。 如果 override 为真值，则如果在 b 中找到相同的键则 a 中已存在的相应键值对将被替换，否则如果在 a 中没有相同的键则只是添加键值对。 当成功时返回 `0` 或者当引发异常时返回 `-1`。

  2.2 新版功能.

int `PyDict_Update`(PyObject *a, PyObject *b)

  这与 C 中的 `PyDict_Merge(a, b, 1)` 一样，也类似于 Python 中的 `a.update(b)`，差别在于 `PyDict_Update()` 在第二个参数没有 “keys” 属性时不会回退到迭代键值对的序列。 当成功时返回 `0` 或者当引发异常时返回 `-1`。

  2.2 新版功能.

int `PyDict_MergeFromSeq2`(PyObject *a, PyObject *seq2, int override)

  将 seq2 中的键值对更新或合并到字典 a。 seq2 必须为产生长度为 2 的用作键值对的元素的可迭代对象。 当存在重复的键时，如果 override 真值则最后出现的键胜出。 当成功时返回 `0` 或者当引发异常时返回 `-1`。 等价的 Python 代码（返回值除外）:

      def PyDict_MergeFromSeq2(a, seq2, override):
          for key, value in seq2:
              if override or key not in a:
                  a[key] = value

  2.2 新版功能.