Giáo trình tin học chương 1

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History of C and C++ • History of C – Evolved from two other programming languages • BCPL and B – “Typeless” languages – Dennis Ritchie (Bell Laboratories) • Added data typing, other features – Development language of UNIX – Hardware independent • Portable programs – 1989: ANSI standard – 1990: ANSI and ISO standard published • ANSI/ISO 9899: 1990

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Chapter 1 – Introduction to C++ 1 Programming Outline 1. History of C and C++ 2. C++ Standard Library 3. Basics of a Typical C++ Environment 4. Introduction to C++ Programming 5. A Simple Program: Printing a Line of Text 6. Another Simple Program: Adding Two Integers 7. Arithmetic 8. Decision Making: Equality and Relational Operators 9. Introduction to Object Technology  2003 Prentice Hall, Inc. All rights reserved.
2 History of C and C++ • History of C – Evolved from two other programming languages • BCPL and B – “Typeless” languages – Dennis Ritchie (Bell Laboratories) • Added data typing, other features – Development language of UNIX – Hardware independent • Portable programs – 1989: ANSI standard – 1990: ANSI and ISO standard published • ANSI/ISO 9899: 1990  2003 Prentice Hall, Inc. All rights reserved.
3 History of C and C++ • History of C++ – Extension of C – Early 1980s: Bjarne Stroustrup (Bell Laboratories) – “Spruces up” C – Provides capabilities for object-oriented programming • Objects: reusable software components – Model items in real world • Object-oriented programs – Easy to understand, correct and modify – Hybrid language • C-like style • Object-oriented style • Both  2003 Prentice Hall, Inc. All rights reserved.
4 C++ Standard Library • C++ programs – Built from pieces called classes and functions • C++ standard library – Rich collections of existing classes and functions • “Building block approach” to creating programs – “Software reuse”  2003 Prentice Hall, Inc. All rights reserved.
5 Basics of a Typical C++ Environment • C++ systems – Program-development environment – Language – C++ Standard Library  2003 Prentice Hall, Inc. All rights reserved.
6 Basics of a Typical C++ Environment Program is created in Editor Phases of C++ Programs: Disk the editor and stored on disk. Preprocessor Preprocessor program 1. Edit Disk processes the code. Compiler creates Compiler Disk object code and stores 2. Preprocess it on disk. Linker links the object Linker Disk code with the libraries, 3. Compile Primary creates a.out and stores it on disk Memory Loader 4. Link Loader puts program in memory. 5. Load Disk . . . . . . 6. Execute CPU Primary Memory CPU takes each instruction and executes it, possibly storing new data . . . . values as the program . . executes.  2003 Prentice Hall, Inc. All rights reserved.
7 Basics of a Typical C++ Environment • Input/output – cin • Standard input stream • Normally keyboard – cout • Standard output stream • Normally computer screen – cerr • Standard error stream • Display error messages  2003 Prentice Hall, Inc. All rights reserved.
8 Introduction to C++ Programming • C++ language – Facilitates structured and disciplined approach to computer program design • Following several examples – Illustrate many important features of C++ – Each analyzed one statement at a time • Structured programming • Object-oriented programming  2003 Prentice Hall, Inc. All rights reserved.
9 A Simple Program: Printing a Line of Text • Comments – Document programs – Improve program readability – Ignored by compiler – Single-line comment • Begin with // • Preprocessor directives – Processed by preprocessor before compiling – Begin with #  2003 Prentice Hall, Inc. All rights reserved.
1 // Fig. 1.2: fig01_02.cpp 2 // A first program in C++. 3 #include 4 5 // function main begins program execution 6 int main() 7 { 8 std::cout
11 A Simple Program: Printing a Line of Text • Standard output stream object – std::cout – “Connected” to screen –
12 1.21 A Simple Program: Printing a Line of Text Escape Sequence Description \n Newline. Position the screen cursor to the beginning of the next line. \t Horizontal tab. Move the screen cursor to the next tab stop. \r Carriage return. Position the screen cursor to the beginning of the current line; do not advance to the next line. \a Alert. Sound the system bell. \\ Backslash. Used to print a backslash character. \" Double quote. Used to print a double quote character.  2003 Prentice Hall, Inc. All rights reserved.
1 // Fig. 1.5: fig01_05.cpp 2 // Printing multiple lines with a single //statement 3 #include 4 5 // function main begins program execution 6 int main() Using newline characters to print on multiple lines. 7 { 8 std::cout
14 Another Simple Program: Adding Two Integers • Variables – Location in memory where value can be stored – Common data types • int - integer numbers • char - characters • double - floating point numbers – Declare variables with name and data type before use int integer1; int integer2; int sum; – Can declare several variables of same type in one declaration • Comma-separated list int integer1, integer2, sum;  2003 Prentice Hall, Inc. All rights reserved.
15 Another Simple Program: Adding Two Integers • Input stream object – >> (stream extraction operator) • Used with std::cin • Waits for user to input value, then press Enter (Return) key • Stores value in variable to right of operator – Converts value to variable data type • = (assignment operator) – Assigns value to variable – Binary operator (two operands) – Example: sum = variable1 + variable2;  2003 Prentice Hall, Inc. All rights reserved.
1 // Fig. 1.6: fig01_06.cpp 2 // Addition program. 3 #include 5 // function main begins program execution 6 int main() 7 { 8 int integer1; // first number to be input by user 9 int integer2; // second number to be input by user 10 int sum; // variable in which sum will be stored 11 std::cout > integer1; // read an integer 13 std::cout > integer2; // read an integer 15 sum = integer1 + integer2; // assign result to sum 16 std::cout
17 Arithmetic • Arithmetic calculations – * • Multiplication – / • Division • Integer division truncates remainder – 7 / 5 evaluates to 1 – % • Modulus operator returns remainder – 7 % 5 evaluates to 2  2003 Prentice Hall, Inc. All rights reserved.
18 Arithmetic • Rules of operator precedence – Operators in parentheses evaluated first • Nested/embedded parentheses – Operators in innermost pair first – Multiplication, division, modulus applied next • Operators applied from left to right – Addition, subtraction applied last • Operators applied from left to right Operator(s) Operation(s) Order of evaluation (precedence) () Parentheses Evaluated first. If the parentheses are nested, the expression in the innermost pair is evaluated first. If there are several pairs of parentheses “on the same level” (i.e., not nested), they are evaluated left to right. *, /, or % Multiplication Division Evaluated second. If there are several, they re Modulus evaluated left to right. + or - Addition Evaluated last. If there are several, they are Subtraction evaluated left to right.  2003 Prentice Hall, Inc. All rights reserved.
19 Decision Making: Equality and Relational Operators • if structure – Make decision based on truth or falsity of condition • If condition met, body executed • Else, body not executed • Equality and relational operators – Equality operators • Same level of precedence – Relational operators • Same level of precedence – Associate left to right  2003 Prentice Hall, Inc. All rights reserved.
20 Decision Making: Equality and Relational Operators Sta nd a rd a lg eb ra ic C++ e q ua lity Exa m p le Me a ning of eq ua lity op era tor or o r re la tio na l of C++ C++ c o nd ition re la tiona l op era tor o p e ra to r c o nd ition Relational operators > > x > y x is greater than y < < x < y x is less than y ≥ >= x >= y x is greater than or equal to y ≤