Computer Programming (1) Lecture Notes PDF

Computer Programming (1) Lecture No.4: Variables , input , memory Lecturer: Dr. Khaled Mohammed bin Abdl Department of Information Technology, College of Applied Science, Seyion University Semester 1, 2023...

Computer Programming (1) Lecture No.4: Variables , input , memory Lecturer: Dr. Khaled Mohammed bin Abdl Department of Information Technology, College of Applied Science, Seyion University Semester 1, 2023 1  Content 2  Variables  C++ Built in data types  C++ variable declaration syntax  cin statement  Local and global variables  Scope resolution operator (::)  Variables and RAM  Defining constants  Typecasting  Enumerated data types  Variable 3  Location on computer’s memory to store data then use and change its value in a program  Each variable has 1. Name (identifier) ◼ Series of letters, digits, underscores ◼ Not a keyword ◼ Start with a letter ◼ Case sensitive ◼ Meaningful 2. Type ◼ Programmer-defined  Determine which of the following variables name is valid or invalid : 4 _under_bar_ z2 h22 2h 67h2 his_account_total t5 87 m928134 her_sales 3g j7 a b c  C++ Built-in Data Types 5  Called fundamental types or primitives types: numeric, character, logical  Data Type 6  Bool ❖ Hastwo values, true and false ❖ Manipulate logical (Boolean) expressions ❖ true and false are called logical values ❖ bool, true, and false are reserved word ❑ Char ❖ Used for characters: letters, digits, and special symbols ❖ Each character is enclosed in single quotes, examples: 'A', 'a', '0', '*', '+', '$', '&' ❖ A blank space is a character and is written ' ' with a space left between the single quotes  Declaring Variables 7  All variables must be declared anywhere in program with a name and data type before they used  Syntax rule: begin with a data type then variable name dataType varName;  Variables of the same type can be declared in  Multiple lines int num1;  One line separated by int num2; int num3; commas int num1, num2, num3;  Initializing Variable 8  Variables can be initialized once declared int first=13, second=10; char ch=' '; double x=12.6, y=123.456;  first and second are int variables with the values 13 and 10, respectively  ch is a char variable whose value is empty  x and y are double variables with 12.6 and 123.456, respectively  Using cin 9  Namespace, std:: ❖ Specifies using a name that belongs to “namespace” std ❖ Can be removed through use of using statements  Standard output stream object, std::cin ❖ “Connected” to keyboard ❖ Defined in input/output stream header file  Stream extraction operator >> ❖ Value to left (left operand) inserted into right operand ❖ Waits for user to input value then press Enter key  Example, std::cin >> num1; ❖ Inserts the standard input from keyboard into variable num1  cin and cout facilitate interaction between user and program 1 // Fig. 2.5: fig02_05.cpp 2 // Addition program that display the sum of two numbers. 3 #include // allow program to perform input and output 4 5 // function main begins program execution 6 int main() 7 { 8 // variable declaration Declare integer variables. 9 int number1; // first integer to add 10 int number2; // second integer to add 11 Use and int sum; // sum of number1 stream extraction number2 12 operator with standard input 13 std::cout > number1; // read first integer from user to number1 15 Calculations can be performed in output statements: alternative for 16 std::cout > number2; // read second integer from user to number2 18 Stream manipulator std::cout