AP计算机教程5-6：中等多选题

于2018年5月22日2018年5月22日由陈欣发布

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How many stars are output when the following code is executed?

for (int i = 0; i < 5; i++) {
   for (int j = 0; j < 5; j++)
      System.out.println("*");
}

Which of the following code segments will produce the displayed output?

1
22
333
4444
55555

for (int i = 1; i <= 5; i++) {
  for (int j = i; j > 0; j--) {
    System.out.print(i);
  }
  System.out.println();
}

for (int i = 0; i < 5; i++) {
  for (int j = 0; j < i; j++) {
    System.out.print(i);
  }
  System.out.println();
}

for (int i = 1; i < 5; i++) {
  for (int j = i; j > 0; j--) {
    System.out.print(i);
  }
  System.out.println();
}

for (int i = 1; i < 6; i++) {
  for (int j = 0; j < i; j++) {
    System.out.println(i);
  }
}

for (int i = 0; i < 5; i++) {
  for (int j = 0; j < i; j++) {
    System.out.print(i+1);
  }
  System.out.println();
}

首先排除每个数换行的IV。对于II，第一行不输出1。对于III，总共只输出四行。对于V，第一行输出数为零个。

What is printed as a result of the following code segment?

for (int k = 0; k < 20; k+=2) {
   if (k % 3 == 1)
      System.out.println(k + " ");
}

0 2 4 6 8 10 12 14 16 18

4 16

0 6 12 18

1 4 7 10 13 16 19

4 10 16

注意k的范围仅限小于20的偶数，除三余一的话只剩下4、10和16。

Which of the following code segments will produce the displayed output?

1 1 1 1 1
2 2 2 2
3 3 3
4 4
5

for (int j = 1; j <= 5; j++) {
  for (int k = 5; k >= j; k--) {
    System.out.print(j + " ");
  }
  System.out.println();
}

for (int j = 1; j <= 5; j++) {
  for (int k = 5; k >= 1; k--) {
    System.out.print(j + " ");
  }
  System.out.println();
}

for (int j = 1; j <= 5; j++) {
  for (int k = 1; k <= j; k++) {
    System.out.print(j + " ");
  }
  System.out.println();
}

for (int j = 1; j <= 5; j++) {
  for (int k = 1; k <= 5; k++) {
    System.out.println(j + " ");
  }
}

for (int j = 1; j <= 5; j++) {
  for (int k = j; k <= 5; k++) {
    System.out.print(k + " ");
  }
  System.out.println();
}

首先排除每个数换行的IV。因为第一行一直显示1，可以排除每列输出变化的V。因为第一行输出5个数，而第五行只有1个数，满足这个的内层循环只有I。

What are the values of var1 and var2 after the following code segment is executed and the while loop finishes?

int var1 = 0;
int var2 = 2;

while ((var2 != 0) && ((var1 / var2) >= 0))
{
   var1 = var1 + 1;
   var2 = var2 - 1;
}

var1 = 0, var2 = 2

var1 = 1, var2 = 1

var1 = 3, var2 = -1

var1 = 2, var2 = 0

The loop won’t finish executing because of a division by zero

由于短路求解，&&后接的第二个条件在第一个已经为false时不会被执行。

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