2 Data Types and Expressions C# Programming: From Problem Analysis to Program Design 3rd Edition C# Programming: From Problem Analysis to Program Design
Part II C# Programming: From Problem Analysis to Program Design
Assignment Statements • Used to change the value of the variable • Assignment operator (=) • Syntax • variable = expression; • Expression can be: • Another variable • Compatible literal value • Mathematical equation • Call to a method that returns a compatible value • Combination of one or more items in this list C# Programming: From Problem Analysis to Program Design
Examples of Assignment Statements int numberOfMinutes, count, minIntValue; char firstInitial, yearInSchool, punctuation; numberOfMinutes = 45; count = 0; minIntValue = -2147483648; firstInitial = ‘B’; yearInSchool = ‘1’; enterKey = ‘\n’; // newline escape character C# Programming: From Problem Analysis to Program Design
Examples of Assignment Statements (continued) double accountBalance, weight; decimal amountOwed, deficitValue; bool isFinished; accountBalance = 4783.68; weight = 1.7E-3; //scientific notation may be used amountOwed = 3000.50m; // m or M must be suffixed to // decimal deficitValue = -322888672.50M; C# Programming: From Problem Analysis to Program Design
Examples of Assignment Statements (continued) int count = 0, newValue = 25; string aSaying, fileLocation; aSaying = “First day of the rest of your life!\n "; fileLocation = @”C:\CSharpProjects\Chapter2”; isFinished = false; // declared previously as a bool count = newValue; @ placed before a string literal signals that the characters inside the double quotation marks should be interpreted verbatim C# Programming: From Problem Analysis to Program Design
Examples of Assignment Statements (continued) Figure 2-7 Impact of assignment statement C# Programming: From Problem Analysis to Program Design
Arithmetic Operations • Simplest form of an assignment statement • resultVariable = operand1 operator operand2; • Readability • Space before and after every operator C# Programming: From Problem Analysis to Program Design
Basic Arithmetic Operations • Modulus operator with negative values • Sign of the dividend determines the result • -3 % 5 = -3; 5 % -3 = 2; -5 % -3 = -3; Figure 2-8 Result of 67 % 3 C# Programming: From Problem Analysis to Program Design
Basic Arithmetic Operations (continued) • Plus (+) with string Identifiers • Concatenates operand2 onto end of operand1 string result; string fullName; string firstName = “Rochelle”; string lastName = “Howard”; fullName = firstName + “ “ + lastName; C# Programming: From Problem Analysis to Program Design
Concatenation Figure 2-9 String concatenation C# Programming: From Problem Analysis to Program Design
Basic Arithmetic Operations (continued) • Increment and Decrement Operations • Unary operator • num++; // num = num + 1; • --value1; // value = value – 1; • Preincrement/predecrement versus post int num = 100; System.Console.WriteLine(num++); // Displays 100 System.Console.WriteLine(num); // Display 101 System.Console.WriteLine(++num); // Displays 102 C# Programming: From Problem Analysis to Program Design
Basic Arithmetic Operations (continued) • int num = 100; • System.Console.WriteLine(x++ + “ “ + ++x); // Displays 100 102 Figure 2-11 Change in memory after count++; statement executed C# Programming: From Problem Analysis to Program Design
Basic Arithmetic Operations (continued) Figure 2-12 Results after statement is executed C# Programming: From Problem Analysis to Program Design
Compound Operations • Accumulation • += C# Programming: From Problem Analysis to Program Design
Basic Arithmetic Operations (continued) • Order of operations • Order in which the calculations are performed • Example • answer = 100; • answer += 50 * 3 / 25 – 4; • 50 * 3 = 150 • 150 / 25 = 6 • 6 – 4 = 2 • 100 + 2 = 102 C# Programming: From Problem Analysis to Program Design
Order of Operations • Associatively of operators • Left • Right C# Programming: From Problem Analysis to Program Design
Order of Operations (continued) Figure 2-13 Order of execution of the operators C# Programming: From Problem Analysis to Program Design
Mixed Expressions • Implicit type coercion • Changes int data type into a double • No implicit conversion from double to int Figure 2-14 Syntax error generated for assigning a double to an int C# Programming: From Problem Analysis to Program Design
Mixed Expressions (continued) • Explicit type coercion • Cast • (type) expression • examAverage = (exam1 + exam2 + exam3) / (double) count; int value1 = 0, anotherNumber = 75; double value2 = 100.99, anotherDouble = 100; value1 = (int) value2; // value1 = 100 value2 = (double) anotherNumber; // value2 = 75.0 C# Programming: From Problem Analysis to Program Design
Formatting Output • You can format data by adding dollar signs, percent symbols, and/or commas to separate digits • You can suppress leading zeros • You can pad a value with special characters • Place characters to the left or right of the significant digits • Use format specifiers C# Programming: From Problem Analysis to Program Design
Formatting Output C# Programming: From Problem Analysis to Program Design
Numeric Format Specifiers C# Programming: From Problem Analysis to Program Design
Custom Numeric Format Specifiers C# Programming: From Problem Analysis to Program Design
Custom Numeric Format Specifiers C# Programming: From Problem Analysis to Program Design
Programming Example – CarpetCalculator Figure 2-15 Problem specification sheet for the CarpetCalculator example C# Programming: From Problem Analysis to Program Design
Data Needs for the CarpetCalculator C# Programming: From Problem Analysis to Program Design
Non-changing Definitions for the CarpetCalculator C# Programming: From Problem Analysis to Program Design
CarpetCalculator Example Figure 2-16 Prototype for the CarpetCalculator example C# Programming: From Problem Analysis to Program Design
Algorithm for CarpetCalculator Example Figure 2-17 CarpetCalculator flowchart C# Programming: From Problem Analysis to Program Design
Algorithm for the CarpetCalculator Example(continued) Figure 2-18 Structured English for the CarpetCalculator example C# Programming: From Problem Analysis to Program Design
CarpetCalculator Example (continued) Figure 2-19 Class diagram for the CarpetCalculator example C# Programming: From Problem Analysis to Program Design
/* CarpetCalculator.cs Author: Doyle */ using System; namespace CarpetExample { class CarpetCalculator { staticvoid Main( ) { constint SQ_FT_PER_SQ_YARD = 9; constint INCHES_PER_FOOT = 12; conststring BEST_CARPET = "Berber"; conststring ECONOMY_CARPET = "Pile"; int roomLengthFeet = 12, roomLengthInches = 2, roomWidthFeet = 14, roomWidthInches = 7; doubleroomLength, roomWidth, carpetPrice, numOfSquareFeet, numOfSquareYards, totalCost; C# Programming: From Problem Analysis to Program Design
roomLength = roomLengthFeet + (double) roomLengthInches / INCHES_PER_FOOT; roomWidth = roomWidthFeet + (double) roomWidthInches / INCHES_PER_FOOT; numOfSquareFeet = roomLength * roomWidth; numOfSquareYards = numOfSquareFeet / SQ_FT_PER_SQ_YARD; carpetPrice = 27.95; totalCost = numOfSquareYards * carpetPrice; Console.Out.WriteLine("The cost of " + BEST_CARPET + " is {0:C}", totalCost); Console.Out.WriteLine( ); carpetPrice = 15.95; totalCost = numOfSquareYards * carpetPrice; Console.Out.WriteLine("The cost of " + ECONOMY_CARPET + " is " + "{0:C}", totalCost); Console.Read(); } } } C# Programming: From Problem Analysis to Program Design
CarpetCalculator Example (continued) Figure 2-20 Output from the CarpetCalculator program C# Programming: From Problem Analysis to Program Design
Coding Standards • Naming Conventions • Identifiers • Spacing Conventions • Declaration Conventions C# Programming: From Problem Analysis to Program Design
Chapter Summary • Memory representation of data • Bits versus bytes • Number system • Binary number system • Character sets • Unicode C# Programming: From Problem Analysis to Program Design
Chapter Summary (continued) • Memory locations for data • Relationship between classes, objects, and types • Predefined data types • Integral data types • Floating-point types • Decimaltype • Boolean variables • Strings C# Programming: From Problem Analysis to Program Design
Chapter Summary (continued) • Constants • Assignment statements • Order of operations • Formatting output C# Programming: From Problem Analysis to Program Design
