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.

Difference between Binary mode and Text Mode in C programming

There are mainly three difference between binary and text mode. They are as follow. i. In text mode, a special character EOF whose ASCII value is 26 is inserted after the last character in the file to mark the end of file. But, there is no such special character present in the binary mode. The binary mode files keep track of the end of file from the number of characters present in the directory entry of the file. ii. In text mode of file, text and numbers are stored as one character per byte. For example, the number 1234 occupies two bytes in memory but it occupies 4 bytes (one byte per character) in the file. But, in binary mode, the number occupies the number of bytes as it occupies in the memory. Thus, the above number occupies two bytes in file also in the case o...

Types of Functions in C Programming

C program has two types of functions: 1. Library Functions 2. User defined functions Library Functions: These are the functions which are already written, compiled and placed in C Library and they are not required to be written by a programmer. The function’s name, its return type, their argument number and types have been already defined. We can use these functions as required. For example: printf(), scanf(), sqrt(), getch(), etc. User defined Functions: These are the functions which are defined by user at the time of writing a program. The user has choice to choose its name, return type, arguments and their types. The job of each user defined function is as defined by the user. A complex C program can be divided into a number of user defined functions. For example: #inlcude<stdio.h> double convert (int) ; /* function proto type */ main() { int c ; /* double d ; */ printf (“Enter temperature in Celsius: ”) ; scanf (“%d”, &c) ; /* d =...

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 ...

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