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Announcements

The CS150 course website is up and running. Access lecture slides, assignments, and lab notes in Microsoft PowerPoint, Word, or PDF format through the provided link.

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Announcements

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  1. Announcements • Website is up! • http://zeus.pacificu.edu/shereen/CS150 • All lecture slides, assignments, lab notes will be available on this site in two forms: • Microsoft PowerPoint or Word • PDF (Acrobat Reader) CS150 Introduction to Computer Science 1

  2. Implementation //Program purpose: converts distance in miles to kilometers //Author: Friedman & Koffman //Date: August 30, 2000 #include <iostream> int main() { using namespace std; const float KM_PER_MILE = 1.609; float miles, kms; //Get the distance in miles cout << “Enter the distance in miles”; cin >> miles; //Convert the distance to kilometers kms = KM_PER_MILE*miles; //Display the distance in kilometers cout << “The distance in kilometers is” << kms << endl; } CS150 Introduction to Computer Science 1

  3. C++ Language Elements • Comments are • how you explain in English what your program does • Ignored by the compiler • Very, very, very important • Format of comments: //comment /* comment */ CS150 Introduction to Computer Science 1

  4. Compiler directives • #include <iostream> • # signifies compiler directive • Processed BEFORE program translation • #include tells the compiler to look for libraries • <> signifies part of standard C++ libraries • We’ll see other examples later of compiler directives CS150 Introduction to Computer Science 1

  5. Namespace std • using namespace std; • Indicates that we will be using objects that are named in a region called namespace std. • The statement ends in a semicolon. • The statement appears in all our programs. CS150 Introduction to Computer Science 1

  6. Main function definition int main( ) { main program } • Your main program is where execution starts. • Every program has one! CS150 Introduction to Computer Science 1

  7. Program statements • Declaration Statements • What data is needed by the program? • const float KM_PER_MILE = 1.609; • float miles, kms; • Executable Statements • Everything else • Examples: • cout, cin • Assignment • All end with semicolon ; CS150 Introduction to Computer Science 1

  8. Identifiers • Names used in program • Examples: • Variables • Functions • Rules: • Begin with letter or underscore • Consist of letters, digits and underscore • Cannot use reserved word CS150 Introduction to Computer Science 1

  9. Identifiers, Contd. • Reserved Words examples • const, float, int, return, main • Complete list in Appendix B of text • Case sensitive • Valid or Invalid? Letter1 joe’s 1letter cent_per_inch Inches two-dimensional Inches*num hello CS150 Introduction to Computer Science 1

  10. Data Types and Declarations • A data type is a way to represent a particular set of values • Four types • Integers • Reals • Booleans • Characters CS150 Introduction to Computer Science 1

  11. Integers • Whole numbers, positive or negative • Stored as binary number • Datatype is called int • Operations? • Finite • Examples of integer literals are: 123, -23, 0, 32767 CS150 Introduction to Computer Science 1

  12. Reals • Real numbers can contain fractional parts • Stored in floating point format • Datatype is float • Operations? • Examples of float literals are: 1.0, -.1, 0., 12E5, -1E-2 CS150 Introduction to Computer Science 1

  13. Characters • Individual character--letter, digit, symbol • Characters stored as byte • Datatype is char • Operations? • Char literals are enclosed in single quotes and examples include: 'A' 'a' '?' CS150 Introduction to Computer Science 1

  14. Purpose of Datatypes • Different ones allow compiler to know how to represent value • Different datatypes can use different operations • The integer 2 is different from 2.0 and the character 2 (all stored differently) CS150 Introduction to Computer Science 1

  15. Declarations • Declarations are at the beginning of a program • They list the variables used • Format: datatype identifier; CS150 Introduction to Computer Science 1

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