Midterm Review Questions Solutions

1. Write a function called isPositive(x) that returns true if x is greater than 0, and false if x is 0 or less. For example:

   isPositive(0) returns false

   isPositive(4.0) returns true

   isPositive(-5.3) returns false

   Sample solution:

   boolean isPositive(float x) {
           if (x > 0) {
                   return true;
           } else {
                   return false;
           }
   }
   
   // or ...
   boolean isPositive(float x) {
           return x > 0;
   }
   

2. Write a function called sign(x) that returns the sign of x, i.e. -1 of x is less than 0, 0 if x is equal to 0, and 1 if x is greater than 0. For example:

   sign(-4) returns -1

   sign(-5.3) returns -1

   sign(0) returns 0

   sign(4) returns 1

   sign(53.2) returns 1

   Sample Solution:

   int sign(float x) {
           if (x < 0) {
                   return -1;
           } else if (x > 0) {
                   return 1;
           } else {
                   return 0;
           }
   }
   

3. Write a function called min(x, y) that returns the smaller of x and y. For example:

   min(1, 2) returns 1

   min(2, 1) returns 1

   min(-85, 2) returns 2

   min(3, 3) returns 3

   Sample solution:

   int min(int x, int y) {
           if (x < y) {
                   return x;
           } else {
                   return y;
           }
   }
   

4. Write a function called dist(x, y) that returns the positive difference between x and y.

   dist(1, 2) returns 1

   dist(2, 1) returns 1

   dist(-5, 2) returns 7

   dist(3, 3) returns 0

   Sample solution:

   int dist(int x, int y) {
           float d = x – y;
           if (d < 0) {
                   return -d;
           } else {
                   return d;
           }
   }
   
   // or ...
   int dist(int x, int y) {
           return abs(x - y);
   }