Top C-plus-plus Interview Questions

A static variable tells the compiler to persist the variable until the end of program. Instead of creating and destroying a variable every time when it comes into and goes out of scope, static is initialized only once and remains into existence till the end of program.

void test();
main()
{
test();
test();
test();
}
void test()
{
static int a = 0; //Static variable
a = a+1;
printf("%d\t",a);
}
Output : 1 2 3

In C++ language, each variable has a storage class which decides scope, visibility and lifetime of that variable. The following storage classes
are most oftenly used in C++ programming:

1. Automatic variables: A variable declared inside a function without any storage class specification, is by default an automatic variable. They are created when a function is called and are destroyed automatically when the function exits.
Example:
void main()
{
int Arjun; or auto int Arjun;
}

2. External variables: A variable that is declared outside any function is a Global variable. Global variables remain available throughout the entire program.
Example:
int number; // global variable
void main()
{
number=10;
}
fun1()
{
number=20;
}
fun2()
{
number=30;
}


3. Static variables: A static variable tells the compiler to persist the variable until the end of program. Instead of creating and destroying a variable every time when it comes into and goes out of scope, static is initialized only once and remains into existence till the end of program.

4. Register variables: Register variable inform the compiler to store the variable in register instead of memory.

Defining multiple functions in a program having same name is called as function overloading. Only precaution to be taken is that function must have different no of or type of argument.
Compiler will decide which to call depending on no. of or type of arguments passed while calling the function.
Example:
# include<iostream.h>
int volume(int L, int B, int H)
{
int v=L*B*H;
return v;
}
int volume(int N)
{
int v=N*N*N;
return v;
}
void main()
{
int a=volume(5,7,8);
cout<<”Volume of box is “<<a;
int b=volume(5);
cout<<”Volume of cube is “<<b;
}

typedef is a keyword used to assign alternative names to existing types. Its mostly used with user defined data types, when names of data types get slightly complicated.
Syntax:
typedef existing_name alias_name