3.12. Programming Exercises

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Review Questions

Section 3.2 boolean Data Type and Operations

3.1	List six comparison operators.
3.2	Assume that x is 1 , show the result of the following Boolean expressions: ( true ) && ( 3 > 4 ) !(x > ) && (x > ) (x > ) (x < ) (x != ) (x == ) (x >= ) (x < ) (x != 1 ) == !(x == 1 )
3.3	Write a Boolean expression that evaluates to true if a number stored in variable num is between 1 and 100 .
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3.4	Write a Boolean expression that evaluates to true if a number stored in variable num is between 1 and 100 or the number is negative.
3.5	Assume that x and y are int type. Which of the following are correct Java expressions? x > y > x = y && y x /= y x or y x and y (x != ) (x = )
3.6	Can the following conversions involving casting be allowed? If so, find the converted result. boolean b = true ; i = (int)b; int i = 1 ; boolean b = ( boolean )i;
3.7	Suppose that x is 1. What is x after the evaluation of the following expression? (x > 1 ) & (x++ > 1 )
3.8	Suppose that x is 1. What is x after the evaluation of the following expression? (x > 1 ) && (x++ > 1 )
3.9	Show the output of the following program: public class Test { public static void main(String[] args) { char x = 'a' ; char y = 'c' ; System.out.println(++y); System.out.println(y++); System.out.println(x > y); System.out.println(x - y); } }

Section 3.3 if Statements

3.10	Suppose x = 3 and y = 2 , show the output, if any, of the following code. What is the output if x = 3 and y = 4 ? What is the output if x = 2 and y = 2 ? Draw a flowchart of the following code: if (x > 2 ) { if (y > 2 ) { int z = x + y; System.out.println( "z is " + z); } } else System.out.println( "x is " + x);
3.11	Which of the following statements are equivalent? Which ones are correctly indented? [Page 91]
3.12	Suppose x = 2 and y = 3 , show the output, if any, of the following code. What is the output if x = 3 and y = 2 ? What is the output if x = 3 and y = 3 ? (Hint: please indent the statement correctly first.) if (x > 2 ) if (y > 2 ) { int z = x + y; System.out.println( "z is " + z); } else System.out.println( "x is " + x);
3.13	Are the following two statements equivalent?
3.14	Which of the following is a possible output from invoking Math.random() ? 323.4 , 0.5 , 34 , 1.0 , 0.0 , 0.234
3.15	How do you generate a random integer i such that i < 20? How do you generate a random integer i such that 10 i < 20? How do you generate a random integer i such that 10 i 50?

Section 3.4 switch Statements

3.16	What data types are required for a switch variable? If the keyword break is not used after a case is processed , what is the next statement to be executed? Can you convert a switch statement to an equivalent if statement, or vice versa? What are the advantages of using a switch statement?
3.17	What is y after the following switch statement is executed? x = 3 ; y = 3 ; switch (x + 3 ) { case 6 : y = 1 ; default : y += 1 ; }
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3.18	Use a switch statement to rewrite the following if statement and draw the flowchart for the switch statement: if (a == 1 ) x += 5 ; else if (a == 2 ) x += 10 ; else if (a == 3 ) x += 16 ; else if (a == 4 ) x += 34 ;

Section 3.5 Conditional Expressions

3.19

Rewrite the following if statement using the conditional operator:

   if   (count %   10   ==     )   System.out.print(count +   "\n"   );   else   System.out.print(count +   " "   ); 

Section 3.6 Formatting Console Output and Strings

3.20	What are the specifiers for outputting a boolean value, a character, a decimal integer, a floating-point number, and a string?
3.21	What is wrong in the following statements? (a) System.out.printf( "%5d %d" , 1 , 2 , 3 ); (b) System.out.printf( "%5d %f" , 1 ); (c) System.out.printf( "%5d %f" , 1 , 2 );
3.22	Show the output of the following statements. (a) System.out.printf( "amount is %f %e\n" , 32.32 , 32.32 ); (b) System.out.printf( "amount is %5.4f %5.4e\n" , 32.32 , 32.32 ); (c) System.out.printf( "%6b\n" , ( 1 > 2 )); (d) System.out.printf( "%6s\n" , "Java" ); (e) System.out.printf( "%-6b%s\n" , ( 1 > 2 ), "Java" ); (f) System.out.printf( "%6b%-s\n" , ( 1 > 2 ), "Java" );
3.23	How do you create a formatted string?

Sections 3.7 “3.8

3.24	List the precedence order of the Boolean operators. Evaluate the following expressions: true true && false true true && false true true & false
3.25	Show and explain the output of the following code: int i = ; System.out.println(i + i + i++); System.out.println(i + ++i); int i = ; i = i + (i = 1 ); System.out.println(i); [Page 93] int i = ; i = (i = 1 ) + i; System.out.println(i);
3.26	Assume that int a = 1 and double d = 1.0 , and that each expression is independent. What are the results of the following expressions? a = (a = 3 ) + a; a = a + (a = 3 ); a += a + (a = 3 ); a = 5 + 5 * 2 % a; a = 4 + 1 + 4 * 5 % (++a + 1 ); d += 1.5 * 3 + (++d); d -= 1.5 * 3 + d++;