Why are local variables not set to zero?
c, c++
Solution
Because such zero-initializations take execution time. It would make your program significantly slower. Each time you call a function, the program would have to execute pointless overhead code, which sets the variables to zero.
Static variables persist for the whole lifetime of the program, so there you can afford the luxuary to zero-initialize them, because they are only initialized once. While locals are initialized in runtime.
It is not uncommon in realtime systems to enable a compiler option which stops the zero initialization of static storage objects as well. Such an option makes the program non-standard, but also makes it start up faster.
Problem
Since global and static variables are initialized to 0 by default, why are local variables not initialized to 0 by default as well?