What is Data Type?
A Data types in a programming language is aset of data with values having predefined characteristics.
Data types whether they are predefined or user defined ,we can never consume them directly .
int =100 ; // invalid
To Consume a Data type we must first create memory allocated for storing the values.
int x=100; // valid
Data Types with Detailed Information :
Value types
to 9223372036854775807
18446744073709551615
floating point type
3.402823e38
floating point type
1.79769313486232e308
character
used in text
types
characters
integral type that can represent
decimal numbers with
29 significant digits
±7.9 × 10e28
Value types
A variable holds actual values then that type of data types are value types.
These value types are stored in “stack” memory and these value types are fixed in size.
If you assign a value of a variable to another variable it will create two copies.
Ex: byte, short, int, float, double, long ,char, bool, DateTime.
- Primitive data types are value types except string, object.
- Object type is superior to all types.
- It can store any type or any size of data. It helps in inheritance process.
- Struct, enum are value types.
Reference types
A variable holds a reference to the value, then that type of data types are reference types.
These reference types are stored in “heap” memory and these types are not fixed in size.
They are maintained in system managed heap but it also uses stack to store reference of the heap.
Two primitive types (string and object) and non-primitive data types (class, interface & delegate) are examples of reference type.
Example .
class Program{ static void Main(string[] args) { // Pass reference type by value ArrayList arrayList = new ArrayList() { 0, 1, 2, 3 }; Console.WriteLine("Pass by Value"); PassByValue(arrayList);
// What should be the output of below line ?? Console.WriteLine(arrayList[1]); arrayList = new ArrayList() { 0, 1, 2, 3 };
Console.WriteLine("Pass by Reference");
PassByReference(ref arrayList);
// What should be the output of below line ?? Console.WriteLine(arrayList[1]);
Console.Read(); }
private static void PassByValue(ArrayList arrayList) {
Console.WriteLine(arrayList[1]); // Now Change the first position value arrayList[1] = 90; arrayList = new ArrayList() { 101, 102, 103, 104 };
Console.WriteLine(arrayList[1]); }
private static void PassByReference(ref ArrayList arrayList) {
Console.WriteLine(arrayList[1]);
// Now Change the first position value arrayList[1] = 90; arrayList = new ArrayList() { 101, 102, 103, 104 };
Console.WriteLine(arrayList[1]); } }
What is meant by Boxing and UnBoxing :
Operators in C#:
An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations. C# has rich set of built-in operators and provides the following type of operators:
- Arithmetic Operators
- Relational Operators
- Logical Operators
- Bitwise Operators
- Assignment Operators
- Misc Operators
This tutorial explains the arithmetic, relational, logical, bitwise, assignment, and other operators one by one.
Arithmetic Operators
Following table shows all the arithmetic operators supported by C#. Assume variable A holds 10 and variable B holds 20 then:
Show Examples
Operator Description Example + Adds two operands A + B = 30 - Subtracts second operand from the first A - B = -10 * Multiplies both operands A * B = 200 / Divides numerator by de-numerator B / A = 2 % Modulus Operator and remainder of after an integer division B % A = 0 ++ Increment operator increases integer value by one A++ = 11 -- Decrement operator decreases integer value by one A-- = 9
Relational Operators
Following table shows all the relational operators supported by C#. Assume variable A holds 10 and variable B holds 20, then:
Show Examples
Operator Description Example == Checks if the values of two operands are equal or not,
if yes then condition becomes true. (A == B) is not true. != Checks if the values of two operands are equal or not,
if values are not equal then condition becomes true. (A != B) is true. > Checks if the value of left operand is greater than the
value of right operand,
if yes then condition becomes true. (A > B) is not true. < Checks if the value of left operand is less than the
value of right operand,
if yes then condition becomes true. (A < B) is true. >= Checks if the value of left operand is greater than or
equal to the value of right operand,
if yes then condition becomes true. (A >= B) is not true. <= Checks if the value of left operand is less than or equal
to the value of right operand,
if yes then condition becomes true. (A <= B) is true.
Logical Operators
Following table shows all the logical operators supported by C#. Assume variable A holds Boolean value true and variable B holds Boolean value false, then:
Show Examples
Bitwise Operators
Operator Description Example && Called Logical AND operator.
If both the operands are non zero then
condition becomes true. (A && B) is false. || Called Logical OR Operator.
If any of the two operands is non zero
then condition becomes true. (A || B) is true. ! Called Logical NOT Operator.
Use to reverses the logical state of its operand.
If a condition is true then Logical
NOT operator will make false. !(A && B) is true.
Bitwise Operators
Bitwise operator works on bits and perform bit by bit operation. The truth tables for &, |, and ^ are as follows:
p q p & q p | q p ^ q 0 0 0 0 0 0 1 0 1 1 1 1 1 1 0 1 0 0 1 1
Assume if A = 60; and B = 13; then in the binary format they are as follows:
A = 0011 1100
B = 0000 1101
-----------------
A&B = 0000 1100
A|B = 0011 1101
A^B = 0011 0001
~A = 1100 0011
The Bitwise operators supported by C# are listed in the following table. Assume variable A holds 60 and variable B holds 13, then:
Show Examples
Operator Description Example & Binary AND Operator copies a bit to
the result if it exists in both operands. (A & B) = 12, which is
0000 1100 | Binary OR Operator copies a bit if
it exists in either operand. (A | B) = 61, which is
0011 1101 ^ Binary XOR Operator copies the bit if
it is set in one operand but not both. (A ^ B) = 49, which is
0011 0001 ~ Binary Ones Complement Operator is
unary and has the effect of 'flipping' bits. (~A ) = 61,
which is
1100 0011 in 2's
complement due
to a signed binary number. << Binary Left Shift Operator.
The left operands value is moved
left by the number of bits specified
by the right operand. A << 2 = 240,
which is 1111 0000 >> Binary Right Shift Operator.
The left operands value is moved right
by the number of bits specified by the right operand. A >> 2 = 15,
which is 0000 1111
Assignment Operators
There are following assignment operators supported by C#:
Show Examples
Operator Description Example = Simple assignment operator,
Assigns values from right side operands
to left side operand C = A + B assigns value
of A + B into C += Add AND assignment operator,
It adds right operand to the left
operand and assign the result to left operand C += A is equivalent to
C = C + A -= Subtract AND assignment operator,
It subtracts right operand from the left
operand and assign the result to left operand C -= A is equivalent to
C = C - A *= Multiply AND assignment operator,
It multiplies right operand with the left
operand and assign the result to left operand C *= A is equivalent to
C = C * A /= Divide AND assignment operator,
It divides left operand with the right
operand and assign the result to left operand C /= A is equivalent to
C = C / A %= Modulus AND assignment operator,
It takes modulus using two operands
and assign the result to left operand C %= A is equivalent to
C = C % A <<= Left shift AND assignment operator C <<= 2 is same as
C = C << 2 >>= Right shift AND assignment operator C >>= 2 is same as
C = C >> 2 &= Bitwise AND assignment operator C &= 2 is same as
C = C & 2 ^= bitwise exclusive OR and assignment operator C ^= 2 is same as
C = C ^ 2 |= bitwise inclusive OR and
assignment operator C |= 2 is same as
C = C | 2
Miscillaneous Operators
There are few other important operators including sizeof, typeof and ? :supported by C#.
| Operator | Description | Example |
|---|---|---|
| sizeof() | Returns the size of a data type. | sizeof(int), returns 4. |
| typeof() | Returns the type of a class. | typeof(StreamReader); |
| & | Returns the address of an variable. | &a; returns actual address of the variable. |
| * | Pointer to a variable. | *a; creates pointer named 'a' to a variable. |
| ? : | Conditional Expression | If Condition is true ? Then value X : Otherwise value Y |
| is | Determines whether an object is of a certain type. | If( Ford is Car) // checks if Ford is an object of the Car class. |
| as | Cast without raising an exception if the cast fails. | Object obj = new StringReader("Hello");
StringReader r = obj as StringReader;
|
Operator Precedence in C#
Operator precedence determines the grouping of terms in an expression. This affects evaluation of an expression. Certain operators have higher precedence than others; for example, the multiplication operator has higher precedence than the addition operator.
For example x = 7 + 3 * 2; here, x is assigned 13, not 20 because operator * has higher precedence than +, so the first evaluation takes place for 3*2 and then 7 is added into it.
Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Within an expression, higher precedence operators are evaluated first.
Category Operator Associativity Postfix () [] -> . ++ - - Left to right Unary + - ! ~ ++ - - (type)*
& sizeof Right to left Multiplicative * / % Left to right Additive + - Left to right Shift << >> Left to right Relational < <= > >= Left to right Equality == != Left to right Bitwise AND & Left to right Bitwise XOR ^ Left to right Bitwise OR | Left to right Logical AND && Left to right Logical OR || Left to right Conditional ?: Right to left Assignment = += -= *=
/= %=>>= <<=
&= ^= |= Right to left Comma , Left to right