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Sunday, 10 May 2015


Today in Engineer's World, we are discussing a very important topic of C# - Data Types in very easy way. Posted By- +Manish Kumar Gautam +LIVE VIAR +ASP.NET SOLUTIONS

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Data Type in a programming language describes that what type of data a variable can hold. The type of data that a variable contains is called Data Type.
C# is a Strongly type typed language so every variable and object must have a type.


1. Basic in-built or primitive or predefined:
Ex- byte, short, int, float, double, long, char, bool, DateTime, string, object,etc.

2. Non-primitive or User-defined:
Ex- enum, class, struct, interface, delegate, array.

The variables in C#, are categorized into the following types:
  • Value types
  • Reference types


A variable which holds the actual values then that type of data types are value types. Value type is stored in "stack" memory and these value types are fixed in size.
Value type variables are local copies. When they fall out of the scope they may die. Value types are derived from System.ValueType.
Ex- byte, short, int, float, double, long, char, bool, DateTime.
Things to Remember:
a) Primitive data type are value type except string.object.
b) struct, enum are value types.
c) The default value, if value is not assigned is 0 for value type(i.e. whether it may int, long, short, char). 

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Example- The default values for value types can be understand by the following example.

Practical Implementation 

using System;

namespace AspnetSolutions
    class Dtype
        public static void Main()
            int a1 = new int();

            char a2 = new char();

            short a3 = new short();



0 //for int default is 0.
   //for char it is ' '.
0 //for short it is 0.

Now, check out Figure 1. This is the most important chart or figure for understanding data types (types, namespace, size, low range of type, high range of type). Interviewer may also asked question like, tell the size in byte taken by decimal or does int variable can store a value 2145656565?
So, I strongly suggest you to look and read this chart to better under data type.


Check out all types one by one:

1. int: An integer is a number with no fractional part; it can be positive, negative or zero. It can store number up to a range that is mentioned in the figure. It represent a 32-bit signed integer.
Namespace & Assembly of type can be checked by Figure-2. All you need is place your mouse pointer on that data type and press F12. Then, you would transfer to its definition. For example- place you mouse pointer on int in your code and Press F12. You will see a similar page as shown in Figure-2.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)


2. bool: Represent a boolean value. Boolean can have only two value it may be true or false.
By default value is false.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

3. char: To represent a single unicode character.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

4. byte: It represent an 8-bit unsigned integer.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

5. short: It represent an 16-bit signed integer.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

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6. float: It represent a single precision floating point number. Float is used to store integer and fractional numbers. But in case of fractional number 'f' would be add to its end.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

7. double: It represent a double precision floating point number.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

8. long: It represent a 64-bit signed integer. 'long' is used to store large number as the range of this type is very large.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

9. DateTime: is used for store and retrieve time. 
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

A variable holds a reference to the value, then that type of data type are reference types. These reference types are stored in "heap" memory and these types are not fixed in size. They are maintained by System managed heap, but it also uses stack to store a reference of the heap.
Two primitive types (string and object), and
Non-primitive data types (class, interface, delegates) are example of reference type.
Ex- class, interface, delegates, string, object and array.
Things to Remember:
a) Object type is superior to all types. It can store any type or any size of data. It helps in Inheritance process.

1. string: It represent text as a Unicode characters.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

2. array: Array can use with any type.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

3. object: can store any type or any size of data.
Namespace -System.
Assembly- mscorlib (mscorlib.dll)

In C# it is possible to convert a value of one type into a value of another type. The operation of Converting a Value Type to a Reference Type is called Boxing and the reverse operation is called Unboxing.
When we declare a variable, we have to tell the compiler about what type of the data the variable can hold or which data type the variable belongs to.

Related Questions: 

#newtoprgm try firstprogram

Q-1 Which of the following are correct about data types?
1. If the integer literal exceeds the range of byte, a compilation error will occur.
2. We cannot implicitly convert non-literal numeric types of larger storage size to byte.
3. Byte cannot be implicitly converted to float.
4. A char can be implicitly converted to only int data type.
5. We can cast the integral character code.

A) 1, 3, 5
B) 2, 4
C) 3, 5
D) 1, 2, 5
Ans- Option(D).

2. Which of the following is an 8-byte integer?
A) Char
B) Long
C) Short
D) Byte
E) Integer
Ans- Option(B).

3. Which of the following is the correct ways to set a value 3.14 in a variable pi such that it cannot be modified?
A) float pi=3.14F;
B) #define pi 3.14F;
C) const float pi = 3.14F;
D) const float pi; pi= 3.14F;
E) pi = 3.14F; 
Ans- Option(C).

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