Question

In the following C program, indicate the variable type (global, local, or static local), the lifetime (when the program is run or when the function is called), and the memory allocation (from stack or from heap) for each variable (x, y, z, and w) defined in the program. int w; void fun (int x) { int y; static float z; ... } void main() { fun(w); }

Answer 1

int w: w is the global variable.

x,y are the local variables or automatic variables .

z is the static local variables

the lifetime and scope of above variables are

The scope of static automatic variables is identical to that of automatic variables, i.e. it is local to the block in which it is defined; however, the storage allocated becomes permanent for the duration of the program.

static storage class provides a lifetime over the entire program, however; it provides a way to limit the scope of such variables, and static storage class is declared with the keyword static as the class specifier when the variable is defined.

the scope of global variables will sustain throughout the program.

Memory Layout of C Programs A typical memory representation of C program consists of following sections. 1. Text segment 2. Initialized data segment 3. Uninitialized data segment 4. Stack 5. Heap high address command-line arguments and environment variables stack heap uninitialized datainitialized to (bss) initialized data text zero by exec read from program file by exec low address

the memory layout of c is