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# introductory concepts

## on Dec 16, 2013

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## introductory conceptsPresentation Transcript

• 2.0 INTRODUCTORY CONCEPT CLO 1, CLO 2 1.Explain various programming problem using design tools (C2) 2. Apply knowledge of basic concepts of fundamental programming to solving a given problem
• 2.0 INTRODUCTORY CONCEPT At the end of this chapter, student will be able to : 1. Define a variable and a constant 2. Identify the rules for naming variables and constant, 3. Declare constants and variables 4. Build constant and variables 5. Explain keywords and operators in programming 6. Use keywords and operators
• 2.0 INTRODUCTORY CONCEPT At the end of this chapter, student will be able to : 7. Convert formula into C expression
• 2.1 Constant And Variables(Identifier) 2.1.1 Variable And Constant Variable • Refer to the memory location where the data is stored • This value keeps changing during the program execution
• Figure 2.1(i) : Representation of Variable in Memory
• 2.1.1 Constant • a location in the memory that stores data that never changes during the execution of the program • constant can either be:  A numbers, like 15 or 10.5  A single character, like 'x' or '#„  A group of characters (string), like “Beautiful Malaysia”
• 2.1.2 Rules For Naming Constants And Variables • Can be a combination of alphabets and numbers but must start with an alphabet • Comprise maximum of 40 characters • No commas or blank space is allowed • No special characters can be used except underscore (_)
• 2.1.3 Declare Constants And Variables • Constant and variable used in a program must be declared in the beginning • To specify the variable and constant data type to the compiler
• Declare Constant const data_type name=value ; e. g : const float pie=3.14 ; const int Days_of_Week=7; const char Colour=“RED”;
• Declare Variable data_type name ; e. g : float mark_1 ; int Quantity; char StudentID;
• 2.1.4 Scope of Constants And Variables DIY
• 2.0 INTRODUCTORY CONCEPT 2.1 Understand Constant And Variables(Identifier) 2.1.5 Build Constants and variables in Programmes Total Pie Payment
• 2.1.6 Identify and Explain Keywords in C Programmes Are reserved words for which the meaning is already defined to the compiler. an identifier cannot have the same spelling and case as a C keyword
• Types Keywords Data types, modifiers and storage class specifiers void, int, char, float, double, signed, unsigned, long, short, auto, const, extern, static, volatile, register and typedef User defined data types and type related struct, Conditional if, else, switch, case and default Flow control for, while, do, break, continue, goto and return union, enum and sizeof
• 2.1.7 Use Keywords In Programmes #include<stdio.h> int main() { printf("Hello worldn"); return 0; }
• 2.1.7 Use Keywords In Programmes #include<stdio.h> main() { int a; printf("Enter an integern"); scanf("%d", &a); printf("Integer that you have entered is %dn", a); return 0;
• 2.1.7 Use Keywords In Programmes #include<stdio.h> main() { char ch; printf("Enter a charactern"); scanf("%c",&ch); if ( ch == 'a' || ch == 'A' || ch == 'e' || ch == 'E' || ch == 'i' || ch == 'I' || ch =='o' || ch=='O' || ch == 'u' || ch == 'U') printf("%c is a vowel.n", ch); else printf("%c is not a vowel.n", ch); return 0; }
• 2.0 INTRODUCTORY CONCEPT 2.2 Understand Data Types Data Types Data types are used to store various types of data that is processed by program. Data type attaches with variable to determine the number of bytes to be allocate to variable and valid operations which can be performed on that variable
• 2.2.1 Basic Data Types in C The C language provides a lot of basic types. Most of them are formed from one of the four basic arithmetic type identifiers in C (char, int, float and double), and optional specifiers (signed, unsigned, short, long). All available basic arithmetic types are listed below:
• Char Short Short int Signed short Signed short int Int Signed int Long long int signed long signed long int long long long long int signed long long signed long long int float double
• 2.2.2 Basic Data Types Numeric
• Numeric Keyword char int short short int long unsigned char unsigned int unsigned short unsigned long float double Variable Type Character (or string) integer Short integer Short integer Long integer Unsigned character Unsigned integer Unsigned short integer Unsigned long integer Single-precision floating-point (accurate to 7 digits) Double-precision floating-point (accurate to 15 digits) Range -128 to 127 -32,768 to 32,767 -32,768 to 32,767 -32,768 to 32,767 2,147,483,648 to 2,147,483,647 0 to 255 0 to 65,535 0 to 65,535 0 to 4,294,967,295 +/-3.4E10^38 to +/-3.4E10^38 +/-1.7E10^308 to +/1.7E10^308
• Characters C stores character type internally as an integer. Each character has 8 bits so we can have 256 different characters values (0- 255).Character set is used to map between an integer value and a character. The most common character set is ASCII. The char type store only one symbol of data (letter, digit, space, tab and so on).
• Relational Relational operators are used to compare two operands.
• Logical • Logical operators are used to combine two simple statements into a compound statement. • Using logical operators, you can simulate Boolean algebra in C.
• Boolean Boolean operators define the relationships between words or groups of words. True=1 False=0
• 2.3.2 Operators used in programming 3 types : a. Mathematic operators b. Relational operators c. Logical operators
• 2.3.3 a.Arithmetic Operator + / * % ++ -- Action Substraction Addition Divide Multiplication Modulus Division Increment Decrement
• Operator precedence : i)bracket () ii) *,/,% (left to right) iii)+,- (left to right)
• Example 1
• Example 2
• b.Relational Operator < <= > >= == != Meaning Less than Less than or equal Greater than Greater than or equal Equal Not equal
• Statement You will pass the exam only when you get more than 50 in subject 1, subject 2 and subject3. To get a medal, you should either be 1st or 2nd in the race. If your sex is not M, you are girl C Expression if ((subject1>=50)&&(subject2>=50)&&(subject3>=50)) printf("PASS") ; if ((position==1)|| (position==2)) printf("You got medal") ; if (!(sex =='M') ){ printf("You are girl");
• 2.3.5 Formula VS Expression Formula • Equation or a set of instructions that solves a certain type of problems in a prescribed manner. • In a formula, the same set of inputs always produces the same output(s).
• e.g: Net Pay = Gross Pay – Deductions Circle Area = ¶R² Voltage = Current + Resistant R = ρ x L/A
• Expression • Expression in C++ are formed by properly combining operators, variables and constants. • We have already seen some examples of simple arithmetic and logical expression • As algebra, C++ expression can be complex. • Parentheses can be used to force the order of evaluation. An expression may also contain spaces for readability.
• e.g: Gross_pay – deductions (basic_pay + hours * rate) – (socso + premium + loan) (b * b – 4 * a * c) > 0 (gender = = ‘m’) && (age > 20) (gender = = ‘m’ || gender = = ‘f’ ) && age >= 21
• 2.3.6 Convert Formula Into C Formula Expression C Expression Net Pay = Gross Pay – Deductions NetPay = GrossPay – Deductions Area = ¶R² Area = Pie x Radius * Radius V = IR V = Current x Resistant R=L L _ A Resistivity= Rho x(Length/Area)
• 2.3.7 Operand And Operator An operation is an action performed on one or more values either to modify the value held by one or both of the variables or to produce a new value by combining variables. Therefore, an operation is performed using at least one symbol and one value. The symbol used in an operation is called an operator. A variable or a value involved in an operation is called an operand.
• Operator Assignment (=) Arithmetic(+,-…..) Relational(<,>…) Logical(&&,||,!) Area = Pie x Radius * Radius Variable or Value Operand
• 2.3.8 Expressions In Application first + second first – second first * second first / second
• 2.3.8 Expressions In Application diam/2 PI * r * r 2 * PI * r
• 2.3.8 Expressions In Application diam/2 area=PI * r * r circ = 2 * PI * r
• Definition Rules For Naming Declaration Scope CONSTANTS AND Build Keywords VARIABLES Types of Operators Formula VS Expression 2. INTRODUCTORY CONCEPT Basic Data Types Convert Formula into C Expression OPERATORS Operand and Operator AND EXPRESSIONS DATA TYPES