introductiontothecomputerprogramming.pptx

introductiontothecomputerprogramming.pptx

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  Computer Systems & Programming Engr.Beenish Adeel
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  An introduction toC++ Programming
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  Topics to beDiscussed… • The Evolution of Programming Languages • Introduction to C++ • The Mechanism of Creating a C++ Program • Processing a C++ Program • Data Types in C++ • Variables • Declaration of Variables • Initialization of Variables
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  The Evolution ofProgramming Languages 1. Machine language ― Only language computer directly understands ― Defined by hardware design ― Machine-dependent ― Generally consist of strings of numbers ― Ultimately 0s and 1s ― Instruct computers to perform elementary operations ― One at a time ― Cumbersome for humans ― Example: +1300042774 0100 1101 0111 1101 0001 0100 0001 0110 +1400593419 0101 0011 0111 1011 0101 1100 0000 1011 +1200274027 0100 0111 1000 1010 1011 1010 0110 1011
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  2. Assembly language –English-like abbreviations representing elementary computer operations – Clearer to humans – Incomprehensible to computers • Translator programs (assemblers) – Convert to machine language – Example: LOAD BASEPAY ADD OVERPAY STORE GROSSPAY The Evolution of Programming Languages
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  The Evolution ofProgramming Languages 3. High-level languages – e.g. C, C++, BASIC, FORTRAN, Java, Pascal, Ada, Perl – Use common mathematical notations – Single statements accomplish substantial tasks • Assembly language requires many instructions to accomplish simple tasks – Translator programs (compilers) • Convert to machine language – Interpreter programs • Directly execute high-level language programs – Example: grossPay = basePay + overTimePay
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  Introduction to C++ •C++ was developed by Bjarne Stroustrup of AT&T Bell Laboratories in the early 1980's • based on the C language. • started as extension to C (macros and variables) • added new useful, features • nowadays a language of its own • C++ (the next thing after C, though wouldn’t + +C be more appropriate?)
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  The Mechanism ofCreating a C++ Program Editor: Accepts the typing of the source code (or header file). Source file: The file that contains the program you prepared in the editor after you save it. (.cpp) Header file: Header files such as iostream.h Preprocessor: Performs preliminary operations on files before they are passed to the compiler. Compiler: Translates the source code to machine language. Object code: The file containing the translated source code. (.obj) Linker: Links the object file with additional code, such as the library codes. Executable code: The file containing the final product. (.exe)
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  C++ Programming: FromProblem Analysis to Program Design, Fourth Edition 9 The Basics of a C++ Program • Function: collection of statements; when executed, accomplishes something – May be predefined or standard • Syntax: rules that specify which statements (instructions) are legal • Programming language: a set of rules, symbols, and special words • Semantic rule: meaning of the instruction
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  Processing a C++Program #include <iostream> using namespace std; int main() { cout<<"My first C++program."<<endl; return 0; } Sample Run: My first C++ program.
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  • Let uslook at the various parts of the above program − • The C++ language defines several headers, which contain information that is either necessary or useful to your program. For this program, the header <iostream> is needed. • The line using namespace std; tells the compiler to use the std namespace. Namespaces are a relatively recent addition to C++. • The next line '// main() is where program execution begins.' is a single-line comment available in C++. Single-line comments begin with // and stop at the end of the line. • The line int main() is the main function where program execution begins. • The next line cout << "Hello World"; causes the message "Hello World" to be displayed on the screen. • The next line return 0; terminates main( )function and causes it to return the value 0 to the calling process. Processing a C++ Program
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  Data Types inC++ Type Keyword Boolean bool Character char Integer int Floating point float Double floating point double Valueless void Wide character wchar_t • C++ offer the programmer a rich assortment of built-in as well as user defined data types. Following table list down seven basic C++ data types: • Several of the basic types can be modified using one or more of these type modifiers: • Signed • unsigned • short, and • long
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  Data types inC++ Type Typical Bit Width Typical Range Char 1byte -127 to 127 or 0 to 255 unsigned char 1byte 0 to 255 signed char 1byte -127 to 127 Int 4bytes -2147483648 to 2147483647 unsigned int 4bytes 0 to 4294967295 signed int 4bytes -2147483648 to 2147483647 Float 4bytes +/- 3.4e +/- 38 (~7 digits) Double 8bytes +/- 1.7e +/- 308 (~15 digits) long double 8bytes +/- 1.7e +/- 308 (~15 digits) wchar_t 2 or 4 bytes 1 wide character
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  Example 2 #include <iostream> usingnamespace std; int main() { cout << "Size of char : " << sizeof(char) << endl; cout << "Size of int : " << sizeof(int) << endl; cout << "Size of short int : " << sizeof(short int) << endl; cout << "Size of long int : " << sizeof(long int) << endl; cout << "Size of float : " << sizeof(float) << endl; cout << "Size of double : " << sizeof(double) << endl; cout << "Size of wchar_t : " << sizeof(wchar_t) << endl; return 0; }
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  Output Size of char: 1 Size of int : 4 Size of short int : 2 Size of long int : 4 Size of float : 4 Size of double : 8 Size of wchar_t : 4
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  Variables in C++(1) • It is a location in the computer memory which can store data and is given a symbolic name for easy reference. The variables can be used to hold different values at different times during the execution of a program. • To understand more clearly we should study the following statement: Total = 20.00; • In this statement a value 20.00 has been stored in a memory location Total.
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  Declaration of avariable (1) • Before a variable is used in a program, we must declare it. This activity enables the compiler to make available the appropriate type of location in the memory. Syntax: dataType Name; Example: float Total; • You can declare more than one variable of same type in a single single statement i-e. int x,y;
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  • Some validdeclarations are shown here : int i, j, k; char c, ch; float f, salary; double d; • The line int i, j, k; both declares and defines the variables i, j and k; which instructs the compiler to create variables named i, j and k of type int. Declaration of a variable (2)
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  Initialization of variable •When we declare a variable it's default value is undetermined. We can declare a variable with some initial value. Syntax: dataType Name = Value; Example: int a = 20;
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  Example #include <iostream> using namespacestd; int main () { int a, b; // Variable declaration int c; float f; a = 10; // actual initialization b = 20; c = a + b; cout << c << endl ; f = 70.0/3.0; cout << f << endl ; return 0; } RESULT 30 23.3333
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  Exercise • Write aprogram which takes 3 numbers from user, add them and shows the result. • Write a program that ask 4 integer numbers from user and performs addition, subtraction, multiplication and division.
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  THANKS