static Storage Type

As opposed to auto type data, C++ also offers static type data, which, as its name suggests, retains its value even after the function to which it belongs has been executed. The following example illustrates the difference between auto static type data:

//Program 8.2
//Program to differentiate between auto and static type data
#include<iostream.h>
void dummy(void);
void main(void)
{
int iVar;
for(iVar=0; iVar<3; iVar++)
{
dummy();
}
void dummy(void)
{
int iCtr = 1;
cout<<"Function executed"<< iCtr << "time"<< endl;
iCtr++;
}


The Output of Program 8.2 would be:
Funtion executed 1 time
Funtion executed 1 time
Funtion executed 1 time

//Program 8.3
//Program to differentiate between auto and static type data
#include<iostream.h>
void dummy(void);
void main(void)
{
int iVar;
for(iVar=0; iVar<3; iVar++)
{
dummy();
}
}
void dummy(void)
{
static int iCtr=1;
cout<<"Function executed" << iCtr << "time(s)"<<endl;
iCtr++;
}

In the programs shown, the function dummy() is used to print the number of times the function has been called. Execution stops when the value of the variable iCtr in the function main() reaches three.

The output of Program 8.3 would be:
Function executed 1 time(s)
Function executed 2 time(s)
Function executed 3 time(s)

This is because, in Program 8.2 the variable iCtr is declared as auto type data. Therefore, every time the function dummy() is called, the variable gets created and initilized to 1. But the static declaration in Program 8.3 ensures that the variable is declared is declared and initialized only once, that is, when the funtion is invoked the very first time.

Arrays declared as static can be initialized within a function at the time of declaration.