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Programming Fundamentals
- 1. Programming Fundamentals Lecture#03 Delivered By: Hassan iqbal SuperiorCollege Toba Tek Singh
- 2. Basic Elements ofa C++ Program
- 3. Keywords: The predefinedwords of the C++ that are used for special purposes in the source program. Also known as reserved words Always written in lowercase There are 63 keywords in c++. Tokens: In C++, a source program consists of keywords, variables(or identifiers), constants, operators, punctuators. These elements of a c++ program are called tokens.
- 4. Identifier: The uniquenames used in the program to represent the variables, constants, functions, and labels etc. are called identifiers. The name of identifier may be 31 characters long. If the name is more than 31 characters long , then first 31 characters will be used by the compiler. An identifier may: consist of alphabets, digits, and underscore. The first character of identifier name must be an alphabetic letter or underscore. The keywords cannot be used as identifier name.
- 5. Types of identifiers: Standard Identifier There are also predefined identifiers in c++ The predefined identifiers that are used for special purposes in the source program are called the standard identifiers. E.g cin, cout User-defined identifier the identifiers defined by the user in the program are called user-defined identifers. E.g variables, user-defined functions, labels
- 6. Data Types inC++: Data types specifies the type of the data that a variable will hold. The data types defines the set of values and set of operations on those values. Two categories: Standard Data Types The data types that are predefined as a part of language. User defined Data Types The data types defined by the user
- 7. The “int”data type: Data Type Name Storage capacity Range Int 2 bytes -32768 to 32767 Short int 2 bytes -32768 to 32767 Long int 4 bytes -2147483648 to 2147483647 Signed int Default Default Unsigned int 2 bytes 0 to 65535 Unsigned long int 4 bytes 0 to 4294967295
- 8. Real Type Data: The numeric values that have decimal point in them are called real type data. Also known as floating point type data The real type data can be represented as exponential notation i.e in terms of mantissa and exponent. 6432157.0 as 6.432157*10^6 Where 6432157 is mantissa and 6 is the exponent. As 6.432157E6
- 9. The “float” DataType Name Storage Capacity Range Float 4 bytes 3.14*10−38 to 3.4*1038 Double 8 bytes 1.7*10−308 to 1.7*10308 Long double 10 bytes 3.14*10−4932 to 3.4*104932
- 10. The “char” datatype: Used to store a single character such as “a”, “$” etc. When the character is stored into a variable, the ACII value is stored into the variable. The ASCII value of ‘A’ is 65 and ‘a’ is 97. By default the character data type is unsigned because the ASCII values are positive. The range for unsigned ‘char’ data type is from 0 to 255. For signed ‘char’ its -128 to127
- 11. Overflow and Underflow: An overflow occurs when the value assigned to a variable is more than the maximum allowable limit. An underflow occurs when the value assigned to a variable is less then the minimum allowable limit.
- 12. Variables: A quantitywhose value may change during program execution. Used to store program’s input data and results during program execution. There are two basic operations that are performed onto the variables. Declaration Initialization
- 13. Rules for NamingVariables: A variable name may consist of: Letter, digit, underscore The 1st character must be a letter or underscore. Special characters except underscore can’t be used The keyword can’t be used as variable name Blank spaces are not allowed Length may be from 1 to 31 characters A variable name declared for one data type can’t be used for another data type. Both uppercase and lowercase letters can be used C++ is a case sensitive language. The meaningful name should be given to the variable.
- 14. Constants: A quantitywhose value does not change during program execution Types: Literal constants Symbolic constants
- 15. Literal Constants: Theword ‘literal’ means exact or accurate. A literal is a constant having independent value that is used in the program source code. E.g 10,10.5, “excellent” Types: Integer Constant Integer constant must lie within the range of the integer. The +ve and –ve signs can also be used.
- 16. Floating-Point Constant: Letter ‘F’ or ‘L’ is used with the constant to specify its data type. E.g 7.619F, 21.62L Character Constant: A single character enclosed in single quotation marks. E.g ‘a’, ‘+’ String Constant: A string of characters enclosed in double quotation marks is known as string constant. E.g “abc”, “659329”
- 17. Symbolic Constants: isa constant identifer. Once a value is assigned to a symbolic constant, it can’t be changed during program execution. Can be declared in two ways: The ‘const’ keyword Using ‘define’ directive
- 18. The ‘const’keyword: Used to declare a constant identifier E.g const float pi=3.1417; The’ define’ directive: It’s a preprocessor directive Used to define a constant known as constant macro A constant Macro is an identifier, which is assigned a particular constant value Syntax: #define identifier expression # define pi 3.141593
- 19. Difference between define andconst ‘define’ directive ‘const’ Qualifier Used as preprocessor directive Used as a statement Not terminated with the ; Terminated with the ; Data type of constant identifier is not specified Data type is specified
- 20. Operators and Expressions: operators are the special symbols that are used to perform special operations on the data. Arithmetic operators Increment and decrement operator Assignment operator Relational operator Logical operator The ‘sizeof’ operator Categories of operators: unary binary
- 21. Data Type ofan Expression Data types of operands Data type of expression Int, float, long Float int., long Long Int, double, long double Long double
- 22. o Operators precedence: oThe order in which the arithmetic operators are evaluated o Without parenthesis: o All multiplications and divisions first from left to right first o All additions and subtractions are then performed from left to right o Operators associativity: o The order in which the operators of the same precedence are evaluated o For example in case of * and / operators, the operations are performed from left to right
- 23. Operators Associativity (), ++postfix,-- postfix Left to right ++ prefix, ++prefix Left to right *,/,% Left to right +,- Left to right =,+=,-=,*=,/= Right to left
- 24. Assignment Statement Astatement that is used to assign a value to a variable. E.g c=a+b; Rvalue and Lvalue: The rvalue is an operand that can be written on the right side of the assignment operator. It can be a constant value, variable or na expression The lvalue is an operand that can be written on the left side of the assignment operator. It must be a variable. Lvalue can be used as Rvalue but Rvalue cannot be used as Lvalue.
- 25. Compound assignmentStatement: An assignment statement that is used to assign the same value to many variables Also known as multiple assignment statement Compound assignment operator Is a combination of arithmetic operator and the assignment operator
- 26. Simple assignment Statement Assignment Statementusing Compound assignment operator X=x+12 X+=12 x=x-4 X-=4 X=x/3 x/=3 Increment and decrement operator: Postfix, prefix
- 27. Type Casting Explicittype casting Cast operator (type) expression int x; x=(int) 3.156; cout<<x; Implicit type casting Comments: Single line Multi line