Declaration of variable and type casting

Q3. What is difference between dynamic and reference declaration of variable?

Answer: Dynamic initialization is extensively used in object-oriented programming. We can create exactly the type of object needed using information that is known only at the run time.

C++ introduces a new kind of variable known as the reference variable. A reference variable provides an alias (alternative name) for a previously defined variable. For example, if we make the variable sum a reference to the variable total, then sum and total can be used interchangeably to represent the variable.

Q4.What is type casting? explain the use of type casting with suitable example.

When there are two operands of different types in an expression, the lower-type variable is converted to the type of the higher-type variable. For example, if one operand is of type int and other is of float, both are converted into float type. Thus, if data types are mixed in an expression, C++ performs the conversions automatically. This process is called implicit or automatic conversion. An example:

void main()

{ int a=10;

float b=40.5, result;

result=a+b;

cout<<"The sum is "<<result; }

Output:

The sum is 50.5.

In this case, variable a is of type int while b is of type float. While solving the expression a+b, the temporary variable of type float is created to store value of a and then two float values are added. The result is of type float and stored in variable result. Here, data type int is promoted to float. Thus, it is also known as standard data type promotion.

The other implicit conversions are

Int and float -> float

Int and long -> long

Int and double -> double

Long and float -> float

Float and double -> double

But, sometime programmer needs to convert a value from one type to another explicitly in a situation where the compiler will not do it automatically. This type of conversion is called explicit conversion or type casting. An example:

void main()

{ int a=4000;

long result;

result=a*100;

cout<<"The product is "<<result; }

Output:

The product is 6784 // Error!!!!!

The corrected version is:

void main()

{ int a=4000;

long result;

result=long(a)*100; //type casting

cout<<"The product is "<<result; }

Output:

The result is 400000 // correct

Here, while solving the expression long(a)*100 in above program, integer type variable a is converted into long type. For this, a temporary variable of type long is created to store value of a and this long value is multiplied by 100 and result is also of type long. The long result is stored in variable result.

Without casting, the result is not correct. This is because multiplication of two integers (i.e. a and 100) results integer value (i.e. 4000000). But this integer value is beyond the range of integer. Thus, garbage value is stored in result variable.

Passing arrays to functions in C programming

Like any other variables, we can also pass entire array to a function. An array name can be named as an argument for the prototype declaration and in function header. When we call the function no need to subscript or square brackets. When we pass array that pass as a call by reference because the array name is address for that array. /* Program to illustrate passing array to function */ #include<stdio.h> void display(int) ; /* function prototype */ main( ) { int num[5] = {100, 20, 40, 15, 33, i ; clrscr( ) ; printf (“\n The content of array is \n”) ; for (i=0; i<5; i++) display (num[i]) ; /*Pass array element fo fun */ getch{ } ; } void display(int n) { printf (“\t%d”, n ) ; } Output: The content of array is 100 20 40 15 3 /* Program to read 10 numbers from keyboard to store these num into array and then c...

CPU (Central Processing Unit)

PGA reffered as pin grid array in which pins of CPU are lined up in a straight format. SPGA referred as staggered pin grid array. in which pins of CPU are arranged staggered format. LGA reffered to as Land Grid Array in which pins are available within inside the socket but not in the CPU in other words in line grid array, in CPU ther are no pinsbut insteadpins areattached with in a socket which contact with with the CPU. for e.g. LGA775 socket(no pins on cpu) has better cooling system. better contact and better locking(climbing). LGA1155: Letest generation I socket, also reffered as sandy bridge, Turbo boost overclocking. More resent than LGA 1156 socket. LGA1156: ability to north bridge Doul channel DDR3 optional integreted graphics PCI express LGA1366: hi end core i series socket integreted tiple channal memmory controller external control bridge(HUB) Upgrading CPU: need to check its core suppert check multiprocessor supports or not check on the ...

Recursive Function in C programming

If a statement within the body of a function calls the same function, the function is called recursive function. Actually, recursion is a process by which a function calls itself repeatedly until some specified condition has been satisfied. This process is used for repetitive computations in which each action is stated in term of previous result. Many iterative or repetitive problems can be written in this form. To solve a problem using recursive method, two conditions must be satisfied. They are: 1) Problem could be written or defined in term of its previous result. 2) Problem statement must include a stopping condition. /* An example of recursive function to calculate factorial of a number.*/ #include<stdio.h> #include<conio.h...

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