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Lecture-2. Operators and Conditionals. Variables(again???). Type: Representation of “bits” in memory Variables: Name for a memory object. Starts with letters, and may contain letters, numerals and underscores Declaration: Start of program block. Combination of type and variable
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Lecture-2 Operators and Conditionals
Variables(again???) • Type: Representation of “bits” in memory • Variables: Name for a memory object. Starts with letters, and may contain letters, numerals and underscores • Declaration: Start of program block. Combination of type and variable • Assignment: Value for the variable
Example type name int a, b; /* Declaration */ int a = 9; /* Decl. with Initial Value */ b = 2; /* Assignment/Definition */
scanf() Function • Input to the program can be done through scanf() function • Format is same as printf(), except for variable used is attached an “&” • For e.g. scanf(“%d”, &i);
test1.c Follow this link to test1.c on the class web page
Math Library(math.h) Note: For Trigonometric functions, angles are in radians
hypot.c Follow this link to hypot.c on the class web page
In class Exercise -1 • Write a program to calculate the Area • of a triangle. • Prompt the user to enter base and height • Use “float” variables
Conditional Statements(if-else) • if (expression) statement: Execute the statement if the expression is true • if (expression) statement-1 else statement-2 Execute statement-1 if expression is true, else execute statement-2
Relational Operators Relational operators return 1if the condition is true, and 0 if the condition is false. They are used in expressions for conditionals
Logical Operators • ! operator: !(expression) inverts the value of the expression. For example: !0=1, !2.0=0 • && operator: expression1 && expression2 is true if and only if both expressions are true • || operator: expression1 || expression2 is true if any one expression is true
grader.c Follow this link to grader.c on the class web page
Switch-case statement Switch (expression) { case value1: statements1; break; case value2: statements2; break; default: default statements; break; } Expression is an integer expression, and are matched against Case values which also must be integers!
calculator.c Follow this link to calculator.c on the class webpage
In class Exercise - 2 Modify the calculator.c program for floating point variables. You should support all the operations as the original program. Your program should print out an error message incase of “divide by zero” error, and exit gracefully.
Homework-2 Follow this link to Homework-2 on the class webpage