03. operators and-expressions
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The document discusses operators in C# for performing calculations. It covers arithmetic, logical, comparison, assignment, and other operators. It explains operator precedence and describes implicit and explicit type conversions. Expressions are defined as sequences of operators and operands that are evaluated to a single value. Examples are provided to demonstrate the use of various operators and expressions to perform calculations in C#.
![Categories of Operators in C#
Category Operators
Arithmetic + - * / % ++ --
Logical && || ^ !
Binary & | ^ ~ << >>
Comparison == != < > <= >=
Assignment
= += -= *= /= %= &= |=
^= <<= >>=
String concatenation +
Type conversion is as typeof
Other . [] () ?: new
6](https://image.slidesharecdn.com/03-operators-and-expressions-130526130231-phpapp01/85/03-operators-and-expressions-6-320.jpg)
![Other Operators (2)
Member access operator . is used to access
object members
Square brackets [] are used with arrays
indexers and attributes
Parentheses ( ) are used to override the
default operator precedence
Class cast operator (type) is used to cast one
compatible type to another
32](https://image.slidesharecdn.com/03-operators-and-expressions-130526130231-phpapp01/85/03-operators-and-expressions-32-320.jpg)
03. operators and-expressions
- 1. Operators and Expressions Performing Simple Calculations with C# Svetlin Nakov Telerik Corporation www.telerik.com
- 2. Table of Contents 1. Operators in C# and Operator Precedence 2. Arithmetic Operators 3. Logical Operators 4. Bitwise Operators 5. Comparison Operators 6. Assignment Operators 7. Other Operators 8. Implicit and ExplicitType Conversions 9. Expressions 2
- 3. Operators in C# Arithmetic, Logical, Comparison, Assignment, Etc.
- 4. What is an Operator? Operator is an operation performed over data at runtime Takes one or more arguments (operands) Produces a new value Operators have precedence Precedence defines which will be evaluated first Expressions are sequences of operators and operands that are evaluated to a single value 4
- 5. Operators in C# Operators in C# : Unary – take one operand Binary – take two operands Ternary (?:) – takes three operands Except for the assignment operators, all binary operators are left-associative The assignment operators and the conditional operator (?:) are right-associative 5
- 6. Categories of Operators in C# Category Operators Arithmetic + - * / % ++ -- Logical && || ^ ! Binary & | ^ ~ << >> Comparison == != < > <= >= Assignment = += -= *= /= %= &= |= ^= <<= >>= String concatenation + Type conversion is as typeof Other . [] () ?: new 6
- 8. Operators Precedence Precedence Operators Highest () ++ -- (postfix) new typeof ++ -- (prefix) + - (unary) ! ~ * / % + - << >> < > <= >= is as == != & Lower ^ 8
- 9. Operators Precedence (2) Precedence Operators Higher | && || ?: Lowest = *= /= %= += -= <<= >>= &= ^= |= 9 Parenthesis operator always has highest precedence Note: prefer using parentheses, even when it seems stupid to do so
- 11. Arithmetic Operators Arithmetic operators +, -, * are the same as in math Division operator / if used on integers returns integer (without rounding) or exception Division operator / if used on real numbers returns real number or Infinity or NaN Remainder operator % returns the remainder from division of integers The special addition operator ++ increments a variable 11
- 12. Arithmetic Operators – Example 12 int squarePerimeter = 17; double squareSide = squarePerimeter / 4.0; double squareArea = squareSide * squareSide; Console.WriteLine(squareSide); // 4.25 Console.WriteLine(squareArea); // 18.0625 int a = 5; int b = 4; Console.WriteLine( a + b ); // 9 Console.WriteLine( a + b++ ); // 9 Console.WriteLine( a + b ); // 10 Console.WriteLine( a + (++b) ); // 11 Console.WriteLine( a + b ); // 11 Console.WriteLine(12 / 3); // 4 Console.WriteLine(11 / 3); // 3
- 13. Arithmetic Operators – Example (2) 13 Console.WriteLine(11.0 / 3); // 3.666666667 Console.WriteLine(11 / 3.0); // 3.666666667 Console.WriteLine(11 % 3); // 2 Console.WriteLine(11 % -3); // 2 Console.WriteLine(-11 % 3); // -2 Console.WriteLine(1.5 / 0.0); // Infinity Console.WriteLine(-1.5 / 0.0); // -Infinity Console.WriteLine(0.0 / 0.0); // NaN int x = 0; Console.WriteLine(5 / x); // DivideByZeroException
- 14. Arithmetic Operators – Overflow Examples 14 int bigNum = 2000000000; int bigSum = 2 * bigNum; // Integer overflow! Console.WriteLine(bigSum); // -294967296 bigNum = Int32.MaxValue; bigNum = bigNum + 1; Console.WriteLine(bigNum); // -2147483648 checked { // This will cause OverflowException bigSum = bigNum * 2; }
- 17. Logical Operators Logical operators take boolean operands and return boolean result Operator ! turns true to false and false to true Behavior of the operators &&, || and ^ (1 == true, 0 == false) : 17 Operation || || || || && && && && ^ ^ ^ ^ Operand1 0 0 1 1 0 0 1 1 0 0 1 1 Operand2 0 1 0 1 0 1 0 1 0 1 0 1 Result 0 1 1 1 0 0 0 1 0 1 1 0
- 18. Logical Operators – Example Using the logical operators: 18 bool a = true; bool b = false; Console.WriteLine(a && b); // False Console.WriteLine(a || b); // True Console.WriteLine(a ^ b); // True Console.WriteLine(!b); // True Console.WriteLine(b || true); // True Console.WriteLine(b && true); // False Console.WriteLine(a || true); // True Console.WriteLine(a && true); // True Console.WriteLine(!a); // False Console.WriteLine((5>7) ^ (a==b)); // False
- 21. Bitwise Operators Bitwise operator ~ turns all 0 to 1 and all 1 to 0 Like ! for boolean expressions but bit by bit The operators |, & and ^ behave like ||, && and ^ for boolean expressions but bit by bit The << and >> move the bits (left or right) Behavior of the operators|, & and ^: 21 Operation | | | | & & & & ^ ^ ^ ^ Operand1 0 0 1 1 0 0 1 1 0 0 1 1 Operand2 0 1 0 1 0 1 0 1 0 1 0 1 Result 0 1 1 1 0 0 0 1 0 1 1 0
- 22. Bitwise Operators (2) Bitwise operators are used on integer numbers (byte, sbyte, int, uint, long, ulong) Bitwise operators are applied bit by bit Examples: 22 ushort a = 3; // 00000000 00000011 ushort b = 5; // 00000000 00000101 Console.WriteLine( a | b); // 00000000 00000111 Console.WriteLine( a & b); // 00000000 00000001 Console.WriteLine( a ^ b); // 00000000 00000110 Console.WriteLine(~a & b); // 00000000 00000100 Console.WriteLine( a << 1); // 00000000 00000110 Console.WriteLine( a >> 1); // 00000000 00000001
- 23. Bitwise Operators –Tips &Tricks How to get the bit at position p in a number n? How to set the bit at position p to 0? 23 int p = 5; int n = 35; // 00000000 00100011 int mask = 1 << p; // 00000000 00100000 int nAndMask = n & mask; // 00000000 00100000 int bit = nAndMask >> p; // 00000000 00000001 Console.WriteLine(bit); // 1 int p = 5; int n = 35; // 00000000 00100011 int mask = ~(1 << p); // 11111111 11011111 int result = n & mask; // 00000000 00000011 Console.WriteLine(result); // 3
- 24. Bitwise Operators – Tips &Tricks (2) How to set the bit at position p to 1? How to print a binary number to the console? 24 int p = 4; int n = 35; // 00000000 00100011 int mask = 1 << p; // 00000000 00010000 int result = n | mask; // 00000000 00110011 Console.WriteLine(result); // 3 Console.WriteLine( Convert.ToString(result, 2).PadLeft(32, '0')); // 00000000000000000000000000110011
- 27. Comparison Operators Comparison operators are used to compare variables ==, <, >, >=, <=, != Comparison operators example: 27 int a = 5; int b = 4; Console.WriteLine(a >= b); // True Console.WriteLine(a != b); // True Console.WriteLine(a == b); // False Console.WriteLine(a == a); // True Console.WriteLine(a != ++b); // False Console.WriteLine(a > b); // False
- 28. Assignment Operators Assignment operators are used to assign a value to a variable , =, +=, -=, |=, ... Assignment operators example: 28 int x = 6; int y = 4; Console.WriteLine(y *= 2); // 8 int z = y = 3; // y=3 and z=3 Console.WriteLine(z); // 3 Console.WriteLine(x |= 1); // 7 Console.WriteLine(x += 3); // 10 Console.WriteLine(x /= 2); // 5
- 30. Other Operators
- 31. Other Operators String concatenation operator + is used to concatenate strings If the second operand is not a string, it is converted to string automatically 31 string first = "First"; string second = "Second"; Console.WriteLine(first + second); // FirstSecond string output = "The number is : "; int number = 5; Console.WriteLine(output + number); // The number is : 5
- 32. Other Operators (2) Member access operator . is used to access object members Square brackets [] are used with arrays indexers and attributes Parentheses ( ) are used to override the default operator precedence Class cast operator (type) is used to cast one compatible type to another 32
- 33. Other Operators (3) Conditional operator ?: has the form (if b is true then the result is x else the result is y) The new operator is used to create new objects The typeof operator returns System.Type object (the reflection of a type) The is operator checks if an object is compatible with given type 33 b ? x : y
- 34. Other Operators Null-coalescing operator ?? is used to define a default value for both nullable value types and reference types It returns the left-hand operand if it is not null Otherwise it returns the right operand 34 int? x = null; int y = x ?? -1; int? x = 1; int y = x ?? -1; Here the value of y is -1 Here the value of y is 1
- 35. Other Operators – Example Using some other operators: 35 int a = 6; int b = 4; Console.WriteLine(a > b ? "a>b" : "b>=a"); // a>b Console.WriteLine((long) a); // 6 int c = b = 3; // b=3; followed by c=3; Console.WriteLine(c); // 3 Console.WriteLine(a is int); // True Console.WriteLine((a+b)/2); // 4 Console.WriteLine(typeof(int)); // System.Int32 int d = new int(); Console.WriteLine(d); // 0
- 37. Implicit and Explicit Type Conversions
- 38. ImplicitType Conversion Implicit type conversion Automatic conversion of value of one data type to value of another data type Allowed when no loss of data is possible "Larger" types can implicitly take values of smaller "types" Example: 38 int i = 5; long l = i;
- 39. ExplicitType Conversion Explicit type conversion Manual conversion of a value of one data type to a value of another data type Allowed only explicitly by (type) operator Required when there is a possibility of loss of data or precision Example: 39 long l = 5; int i = (int) l;
- 40. Type Conversions – Example Example of implicit and explicit conversions: Note: Explicit conversion may be used even if not required by the compiler 40 float heightInMeters = 1.74f; // Explicit conversion double maxHeight = heightInMeters; // Implicit double minHeight = (double) heightInMeters; // Explicit float actualHeight = (float) maxHeight; // Explicit float maxHeightFloat = maxHeight; // Compilation error!
- 42. Expressions
- 43. Expressions Expressions are sequences of operators, literals and variables that are evaluated to some value Examples: 43 int r = (150-20) / 2 + 5; // r=70 // Expression for calculation of circle area double surface = Math.PI * r * r; // Expression for calculation of circle perimeter double perimeter = 2 * Math.PI * r;
- 44. Expressions (2) Expressions has: Type (integer, real, boolean, ...) Value Examples: 44 int a = 2 + 3; // a = 5 int b = (a+3) * (a-4) + (2*a + 7) / 4; // b = 12 bool greater = (a > b) || ((a == 0) && (b == 0)); Expression of type int. Calculated at compile time. Expression of type int. Calculated at runtime. Expression of type bool. Calculated at runtime.
- 46. Summary We discussed the operators in C#: Arithmetic, logical, bitwise, comparison, assignment and others Bitwise calculations Operator precedence We learned when to use implicit and explicit type conversions We learned how to use expressions 46
- 47. Resources Boolean algebra (logic) http://en.wikipedia.org/wiki/Boolean_algebra_ %28logic%29 Bitwise mask http://en.wikipedia.org/wiki/Mask_%28computi ng%29 Bitwise operation http://en.wikipedia.org/wiki/Bitwise_operation BitTwiddling Hacks graphics.stanford.edu/~seander/bithacks.html 47
- 49. Exercises 1. Write an expression that checks if given integer is odd or even. 2. Write a boolean expression that checks for given integer if it can be divided (without remainder) by 7 and 5 in the same time. 3. Write an expression that calculates rectangle’s area by given width and height. 4. Write an expression that checks for given integer if its third digit (right-to-left) is 7. E. g. 1732 true. 5. Write a boolean expression for finding if the bit 3 (counting from 0) of a given integer is 1 or 0. 6. Write an expression that checks if given point (x, y) is within a circle K(O, 5). 49
- 50. Exercises (2) 7. Write an expression that checks if given positive integer number n (n ≤ 100) is prime. E.g. 37 is prime. 8. Write an expression that calculates trapezoid's area by given sides a and b and height h. 9. Write an expression that checks for given point (x, y) if it is within the circle K( (1,1), 3) and out of the rectangle R(top=1, left=-1, width=6, height=2). 10. Write a boolean expression that returns if the bit at position p (counting from 0) in a given integer number v has value of 1. Example: v=5; p=1 false. 50
- 51. Exercises (3) 11. Write an expression that extracts from a given integer i the value of a given bit number b. Example: i=5; b=2 value=1. 12. We are given integer number n, value v (v=0 or 1) and a position p.Write a sequence of operators that modifies n to hold the value v at the position p from the binary representation of n. Example: n = 5 (00000101), p=3, v=1 13 (00001101) n = 5 (00000101), p=2, v=0 1 (00000001) 51
- 52. Exercises (4) 13. Write a program that exchanges bits 3, 4 and 5 with bits 24, 25 and 26 of given 32-bit unsigned integer. 14. *Write a program that exchanges bits {p, p+1, …, p+k-1) with bits {q, q+1, …, q+k-1} of given 32-bit unsigned integer. 52