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Chapter 1

Chapter 1. Introduction to Programming. Computer Hardware. CPU Memory Main or primary Secondary or auxiliary Input device(s) Output device(s). Computer Program.

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Chapter 1

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  1. Chapter 1 Introduction to Programming

  2. Computer Hardware • CPU • Memory • Main or primary • Secondary or auxiliary • Input device(s) • Output device(s)

  3. Computer Program • A list of instructions that direct the computer hardware to perform a particular data processing tack or solve a specific problem. The program is coded in a particular programming language such as C++, Fortran, and Visual Basic. • Software = a program or a collection of programs

  4. Programming Languages • Low level machine language: 0’s and 1’s; the native language of the machine; machine-dependent. • Intermediate level assembler language: mnemonics; suggestive symbols or letters; Machine dependent; requires translator known as assembler. • High level procedural language: resembles English and/or standard notation of math; machine-independent (portable); requires translator known as compiler or interpreter.

  5. Types of Instructions • Input: e.g., cin in C++ • Process: many operator including +, -, *, / to perform arithmetic and other types of processing. • Output: e.g., cout in C++

  6. Types of Computer Software • Systems software • Operating system: Windows, Unix • Compiler: C/C++ compiler • … • Applications software • Payroll program: usually custom-designed/developed. • Airline reservation software: usually custom-designed/developed; very expensive. • Word processor: perform generic word-processing tasks for general consumers.

  7. Algorithm • Step-by-step instructions that lead to the solution of a problem. • Example: What is the algorithm that computes the average of three arbitrary values? What is the algorithm that adds integers from 1 to 100? (not unique! Some are better or more efficient that others. Efficient in what sense?)

  8. Algorithms continued • Tools to help develop/specify/visualize an algorithm • Flowchart: a set of symbols (p9); less popular today but helpful to beginners to visualize the steps. • Pseudocode: informal English statements; easier to convert to a program using a structured programming language such as C or Fortran.

  9. Computer Problem Solving Steps • Understand/formulate/specify the problem • Develop the algorithm, which is independent of computer languages. • Convert the algorithm to a program (Computer language must be chosen) • Test/debug (steps 1 thru 4 may be iterative) • Deliver

  10. How to run or execute (test) a C++ program • Need a C++ translator known as a compiler, which convert C++ source program (or source code) to machine language program (or object code). • There are several popular C/C++ compilers available commercially or in the public domain: Borland/Turbo C/C++, Microsoft Visual C/C++, gcc compiler, etc.

  11. Turbo C/C++ program development environment • The Integrated Development Environment or IDE • Editor • Preprocessor and compiler • Debugger • Others

  12. A simple C++ program • The program displays/prints a greeting message “Hello World” • Steps 1 and 2 are quite clear, we go straight to steps 3, namely code the program in C++

  13. A simple C++ program continued #include <iostream.h> int main ( ) { cout << “Hello World!” << endl; return 0; }

  14. Another simple program. What does it do? #include <iostream.h> int main ( ) { double x, y, z, avg; cout << “Enter 3 values: “; cin >> x >> y >> z; avg = ( x + y + z ) / 3; cout << “The average of three arbitrary values is “ << avg; return 0; }

  15. C++ language elements (tokens) • Keywords: 62 reserved word including return; each has special meaning and must not be misspelled. • Identifier: names chosen by the programmer; it is usually used to name or identify a memory location (known as a variable) or a function. • Operators: specifies operations • Constants: may be numeric or non-numeric • Punctuation symbols such as ;.

  16. Tokenize the above programs In the two programs • What are the keywords? • What are the identifiers? • What are the punctuators? • What are the constants? • What are the operators?

  17. Question? • What does #include <iostream.h> mean? • What are the rest of the lines in the program for? • Why return 0? • What are cin and cout? • What is >>? • What is <<? • Are the ordering of lines (instructions) in the program important? • Can one use u, v, and w in place of x, y, and z?

  18. Divide and conquer: a modular approach to a complex problem

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