How to share a variable between two functions in C?

Question

In C, suppose var1 is a variable in foo1() and foo2() wants to access var1, however, foo1() doesn\'t call foo2(), so we can\'t pass it by parameter. At the same time, only foo1(

Answer 1

No. The variable only exists on the function stack while foo1() is running. The stack will vanish when leaving the function. You could make the variable static to keep it alive, but then you can't access it from the outside either without hacks.