Lab 5 2012/2012


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Lab 5 2012/2012

  1. 1. UNIVERSITI TUN HUSSEIN ONN MALAYSIA FACULTY OF MECHANICAL AND MANUFACTURING ENGINEERING BTI 10202: COMPUTER PROGRAMMING LAB 5 : Control Statements- Part 1 (Selection) NAME : ____ _______________________________________ MARKS MATRICS NO.: _______________ DATE : _____________Objective: Introduction to various concepts of selection control structure (Be able to choose and use the if, if..else, switch and goto selection structures among alternatives action)Theory:1. if single selection structure Syntax: If the condition is TRUE, a set of if (conditional is true) statements are executed. { If the condition is FALSE, the statement Statement(s); are not executed and the program control } goes to the next statement (after the if next statement block) immediately. Statement executes repeatedly as long as the value of condition remains TRUE.2. if double selection structure (if…else) Syntax: If the condition is TRUE, statement A if (condition is true) executes. When FALSE, statement { executes. statement A; } else { statement B; } Next statement;3. if multiple selection structure (if… Syntax: else if) If (condition A) The ‘else if’ statement is to check for a { sequence of conditions. Statement A; If one condition is false, it checks for the } next condition and so on. When all the else if (condition B) conditions are false, the ‘else’ block is { executed. Statement B; } : : :else if (condition n) { Statement set-n; } else { Statement set-x; }
  2. 2. a. Relational operators b. Equality operators Symbol Meaning Symbol Meaning > greater than == equal to >= greater than or equal to != not equal to < less than <= less than or equal to Note: If the selection structures have a few statements, thenc. Logical operators we need to use the curly bracket { }. Example: Symbol Meaning If (marks>=60) printf(“Grade A”); && AND (Returns true if else if (marks<60&&marks>=30) both conditions printf(“Grade B”); are true) else (marks<30) { || OR (Returns true if printf(“Failed”); either of its printf(“Take a test again!”); } conditions is true ! NOT (Reverses the truth/falsity of its condition)4. switch is useful when variable or Syntax: condition is tested for multiple switch (expression) { values. It consists of a series of case labels and an optional default case expression 1: case. statements1; The switch and case statements break; help control complex conditional and branching operations. case expression 2: statements 2; break; default: expression n; break; }
  3. 3. Note: break is used to terminate loops/ exit from a switch. Can be used within a for,while, do-while or switch statement.5. goto is a unconditional Syntax: branching statement used to transfer goto name_label; control of the program from one : statement to another. Note: please : ensure not to use too much goto name_label: statements in the program because its functionality is limited. It is only recommended as a last resort if structured solutions are much more complicated.Flowchart for selection structures Flowchart for switch control statements (Adapted from Deitel & Deitel, C How to Program, 6th ed., p. 111)Example: start: printf(“1. Apple juicen”); printf(“2. Mango juicen”); printf(“Choose the fruit juice that you like?”); scanf(“%d”,&juice); switch(juice) { case 1: printf(“You like to drink apple juice”);break; case 2: printf(“You like to drink mango juice”);break; default: printf(“None of the fruit juice that you like!”);goto start; break; }Exercises:1. What is the output for the following source code: Output: #include <stdio.h> #include <conio.h> main() { int n = 0; loop:
  4. 4. printf("n%d", n); n++; if (n<10) { goto loop; } getch(); }2. Below is a program to print RED when ‘r’or’R’ is pressed and WHITE when ‘w’ or ‘W’ is pressed using a switch control statement. The program loops back to enter ‘r’or’R’ or ‘w’ or ‘W’ if other keys are pressed. Rewrite the coding using if-else control statements. SWITCH program #include<stdio.h> #include<conio.h> main() { char choice; choose: printf("nPlease enter R for red and W for whiten"); scanf("%s",&choice); switch(choice) { case r: case R:printf(" RED "); break; case w: case W:printf(" WHITE"); break; IF…ELSE program default: printf("Error!!"); goto choose; break; } getch(); }