What do the following loops print? Work out the answer by tracing the code, not

Question

What do the following loops print? Work out the answer by tracing the code, not by using the computer. a. int s = 1; for (int n = 1; n <= 5; n++) { s = s + n; System.out.print(s + " "); }
b. int s = 1; for (int n = 1; s <= 10; System.out.print(s + " ")) { n = n + 2; s = s + n; } c. int s = 1; int n; for (n = 1; n <= 5; n++) { s = s + n; n++; } System.out.print(s + " " + n);

6.19 What do the following program segments print? Find the answers by tracing the code, not by using the computer.
a. int n = 1; for (int i = 2; i < 5; i++) { n = n + i; } System.out.print(n);
b. int i; double n = 1 / 2; for (i = 2; i <= 5; i++) { n = n + 1.0 / i; } System.out.print(i);
c. double x = 1; double y = 1; int i = 0; do { y = y / 2; x = x + y; i++; } while (x < 1.8); System.out.print(i);
d. double x = 1; double y = 1; int i = 0; while (y >= 1.5) { x = x / 2; y = x + y; i++; } System.out.print(i);

Explanation / Answer

What do the following loops print? Work out the answer by tracing the code, not by using the computer.

a. int s = 1; for (int n = 1; n <= 5; n++) { s = s + n; System.out.print(s + " "); }
   
   s = 1 + 1 = 2
   s = 2 + 2 = 4
   s = 4+ 3 = 7
   s = 7+ 4 = 11
   s = 11 +5 = 16
  
   2 4 7 11 16

b. int s = 1; for (int n = 1; s <= 10; System.out.print(s + " ")) { n = n + 2; s = s + n; }

   s = 1 + 3 = 4
   s = 4 + 5 = 9
   s = 9 + 7 = 16

   4 9 16

c. int s = 1; int n; for (n = 1; n <= 5; n++) { s = s + n; n++; } System.out.print(s + " " + n);
  
   s = 1+1 = 2
   s = 2 + 3 = 5
   s = 5 + 5 = 10
   n = 7
  
   10 7

6.19 What do the following program segments print? Find the answers by tracing the code, not by using the computer.

a. int n = 1; for (int i = 2; i < 5; i++) { n = n + i; } System.out.print(n);

   n = 1+2 = 3
   n = 3+3 = 6;
   n = 6+4 = 10;
  
   10

b. int i; double n = 1 / 2; for (i = 2; i <= 5; i++) { n = n + 1.0 / i; } System.out.print(i);

    i will be 6;
  
   6

c. double x = 1; double y = 1; int i = 0; do { y = y / 2; x = x + y; i++; } while (x < 1.8); System.out.print(i);

   y = 1/2
   x = 1 + 1/2 = 1.5
   i = 1
   y = 1/4
   x = 1.5 + 0.25 = 1.75
   i = 2
   y = 1/8
   x = 1.75 + 0.125 = 1.875
   i = 3
   since x > 1.8 loops breaks

   3

d. double x = 1; double y = 1; int i = 0; while (y >= 1.5) { x = x / 2; y = x + y; i++; } System.out.print(i);
since y is not greater than 1.5
i will be 0 and it prints 0

0

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