Control structures.ppt
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The document discusses various control structures in C++ including repetition structures like while, for, do/while and selection structures like switch. It provides examples of each with explanations. Repetition structures like while and for are used to repeatedly execute a block of code until a condition is met. The switch statement allows executing different blocks of code based on the value of an expression. Other flow control statements like break and continue are also covered. Examples are provided to demonstrate calculating a sum using for, checking for prime numbers, and building a basic calculator using switch.
Control structures.ppt
- 1. Control Structures in C++ 1)While 2)do/while, 3)for 4) Switch 5) Break 6)continue
- 2. The while Repetition Structure • Repetition structure – while loop repeated until condition becomes false. • Flow chart: condition statement true false int main() { int x = 2; while (x >= 0) { if ( x == 2) { cout << “Value of x is : “ << x << endl; } x = x – 1; } return 0; } • Common errors: – infinite loop – unitialized variables
- 3. The for Repetition Structure • The general format when using for loops is for ( initialization; LoopContinuationTest; increment ) statement • Example: for( int counter = 1; counter <= 10; counter++ ) cout << counter << endl; – Prints the integers from one to ten
- 4. Flowchart for for Condition Test the variable statement true false Increment variable Initialize variable
- 5. 1 // sum_even.cpp 2 // Summation with for 3 #include <iostream> 4 5 using std::cout; 6 using std::endl; 7 8 int main() 9 { 10 int sum = 0; 11 12 for ( int number = 2; number <= 100; number += 2 ) 13 sum += number; 14 15 cout << "Sum is " << sum << endl; 16 17 return 0; 18 } Sum is 2550 • Program to sum the even numbers from 2 to 100
- 6. The switch Multiple-Selection Structure • switch – Useful when variable or expression is tested for multiple values – Consists of a series of case labels and an optional default case – break is (almost always) necessary
- 7. General form of switch statement: switch (expression) { case val1: statement break; case val2: statement break; …. case valn: statement break; default: statement break; }
- 8. flowchart true false . . . case a case a action(s) break case b case b action(s) break false false case z case z action(s) break true true default action(s)
- 9. The do/while Repetition Structure • The do/while repetition structure is similar to the while structure, – Condition for repetition tested after the body of the loop is executed • Format: do { statement } while ( condition ); • Example (letting counter = 1): do { cout << counter << " "; } while (++counter <= 10); – This prints the integers from 1 to 10 • All actions are performed at least once. true false statement condition
- 10. The break and continue Statements • Break – Causes immediate exit from a while, for, do/while or switch structure – Program execution continues with the first statement after the structure – Common uses of the break statement: • Escape early from a loop • Skip the remainder of a switch structure
- 11. • Continue – Skips the remaining statements in the body of a while, for or do/while structure and proceeds with the next iteration of the loop – In while and do/while, the loop-continuation test is evaluated immediately after the continue statement is executed – In the for structure, the increment expression is executed, then the loop-continuation test is evaluated
- 12. The continue Statement • Causes an immediate jump to the loop test int next = 0; while (true){ cin >> next; if (next < 0) break; if (next % 2) //odd number, don’t print continue; cout << next << endl; } cout << “negative num so here we are!” << endl;
- 13. control statement examples • Problem:1 A college has a list of test results (1 = pass, 2 = fail) for 10 students. Write a program that analyzes the results. If more than 8 students pass, print "Raise Tuition". Problem : 2 Calculating compound interest Where, P=10000 is principle amount R=5 is the rate and T=2 is the time span (Hint:Formula to calculate compound interest annually is given by: Amount= P(1 + R/100)t Compound Interest = Amount – P) Problem :3 Program to build simple calculator using switch statement Problem :4 Write a program to check user entered number is prime or not.