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# Static storage duration

From cppreference.com
< c‎ | language

An object whose identifier is declared without the storage-class specifier _Thread_local, and either with external or internal linkage or with the storage-class specifier static, has static storage duration. Its lifetime is the entire execution of the program and its stored value is initialized only once, prior to program startup.

### [edit] Notes

Since its stored value is initialized only once, an object with static storage duration can profile the invocations of a function.

The other use of the keyword static is file scope.

### [edit] Example

Profiling the invocations of function f().

Run this code

    #include <stdio.h>

    void f (void)
    {
        static int count = 0;   /* static variable    */
        int i = 0;              /* automatic variable */
        printf("%d %d\n", i++,count++);
        return;
    }

    int main(void)
    {
        for (int ndx=0; ndx<10; ++ndx)
            f();

        return 0;
    }

Possible output:

    0 0
    0 1
    0 2
    0 3
    0 4
    0 5
    0 6
    0 7
    0 8
    0 9

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