volatile union
时间: 2023-10-31 11:35:11 浏览: 31
"volatile union" is a C language construct that combines the features of both "union" and "volatile".
A "union" is a special data type in C that allows different data types to be stored in the same memory location. This means that a union variable can hold different values at different times, depending on which member of the union is being accessed.
"Volatile" is a keyword in C that tells the compiler that a variable's value may change at any time, even if it appears not to be modified by the program. This is often used for hardware registers or memory-mapped I/O.
So a "volatile union" is a union where the members may be volatile. This can be useful when dealing with hardware registers or other situations where the value of a variable could change unexpectedly. By declaring the union as volatile, the compiler will ensure that any accesses to the union are not optimized away, and will always reflect the current value of the underlying memory location.