Zookeeper
In C language, data types can be divided into four categories: basic type, construction type, pointer type, and null type.
Basic type: the primary feature of a basic data type is that its values cannot be decomposed into other types. That is to say, the basic data type is the most basic type.
Constructor type: the constructor type is defined based on one or more defined data types. That is to say, the value of a construction type can be divided into several "members" or "elements ". Each "member" is a basic data type or a constructor type. In C, there are several types of constructor: array type, struct type, and shared object (union) type.
Pointer type: A pointer is a special and important data type. The value indicates the address of a variable in the internal memory. We use the pointer type to access the data pointed to by the pointer.
Null type: when calling a function value, a function value is usually returned to the caller. The returned function value has a certain data type and should be described in the function definition and function description. For example, in the max function definition, the function header is int max (int x, int y). The "int" type specifier indicates that the return value of the function is an integer. Another example is that you do not need to return the function value to the caller after calling void printf_hello (). This function can be defined as "null type ". Its type description is void.
