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whose variables are also known as global variables?
The variables which are declared outside the main() function is known as global variables and they can be used anywhere in the program. And, the variables which used declare inside the main() function is known as local variables and they can be used inside the main() function only. Example: #include<stdio.h> #include<conio.h> int x,y; // global variables void main() { int a,b; // Local variables ------------ ---------------------- --------------------- getch(); }
Which variable is not destroyed on exit from the function instead its value is presented and becomes available again when the function is next called These variables are declared as?
Local function variables defined static remain in memory at all times. Such variables are only in scope (accessible) when the function itself is in scope.
Should you avoid local variable scope?
No. In most designs, local variables are considered a good thing thanks to the isolation that they provide (no other code can "abuse" your variable). However, it is important to distinguish between local static variables, local automatic variables, and locally made references to the heap. Local static variables are initialized only once at application initialization time, and retain their most recently assigned value over multiple invocations of the function which contains them. Local static variables must be used with care and can lead to non-reentrant code (the famous example being the strtok() CRT function). However, these variables are usually great to track the total number of something, or the minimum or maximum value of a particular item, etc. In C, local automatic variables are the most common form of local variables. These are typically allocated on the stack, so care must be taken when declaring large automatic variables, or when using recursion. When the size of a local automatic variable is a concern, dynamic memory management method should be considered those maintain a local auto pointer on the stack but place the data in the heap. This method allows to allocate large amounts of data without burden on the stack, and the lifetime of such data is no longer limited by the lifetime of the scope in which it was allocated. Very rare cases exist where local variables are generally avoided; these are mostly in the area of very resource limited embedded programming.
What is the purpose of the program stack?
Its main use is to store local variables, arguments and return address each time a function is called.When your program calls a function the following happen :- The function arguments are put on the stack- The current instruction pointer is put on the stack- The program jumps to the start of the function- Space is allocated on the stack to hold local variables- The function executes- The space holding local variables is de-allocated- The instruction pointer is restored and removed from the stack (we are now leaving the function and resuming the calling procedure)- The arguments are removed from the stack
What are the advantages of local variables in programming?
1. Local variables cannot be used by other forms. 2. Cannot be used globally. 3. They can slowdown the compiling process.
