storage durations

Storage duration

All variables in a program have one of the following storage durations:

• automatic storage duration. The variable is allocated at the beginning of the enclosing code block and deallocated on end. All non-global variables have this storage duration, except those declared static, extern or thread_local.

• static storage duration. The variable is allocated when the program begins and deallocated when the program ends. Only one instance of the variable exists. All global variables have this storage duration, plus those declared with static or extern.

thread storage duration. The variable is allocated when the thread begins and deallocated when the thread ends. Each thread has its own instance of the variable. Only variables declared thread_local have this storage duration. thread_local can appear together with static or extern to adjust linkage.

(since C++11)

• dynamic storage duration. The variable is allocated and deallocated per request by using dynamic memory allocation functions.