The initialization of pointer variables can be completed at the time of definition or after definition, or as an element in an array or structure. For local pointer variables, if there is no explicit initialization assignment operation, its value is uncertain, because declaring a variable only allocates a memory space to it, and the value stored in this memory is uncertain.

What is a pointer? Pointer is a data type in C language, and pointer is the address of the memory unit that stores data. There are a large number of storage units in the memory of a computer system, and the size of each storage unit is 1 byte. In order to facilitate management, each storage unit must be numbered, which is the "address" of the storage unit, and each storage unit has a unique address. Pointer variables can store not only the addresses of variables, but also the addresses of other data, such as arrays and functions.