Programming with M-Files: If-Statement Drill Exercises
Summary: This module provides several simple exercises designed to test and increase your understanding of if statements in m-file scripts.
Some If Statement Exercises
Exercise 1
What will the following code print?
a = 10;
if a ~= 0
disp('a is not equal to 0')
end
Solution 1
' a is not equal to 0'
Exercise 2
What will the following code print?
a = 10;
if a > 0
disp('a is positive')
else
disp('a is not positive')
end
Solution 2
' a is positive'
Exercise 3
What will the following code print?
a = 5;
b = 3;
c = 2;
if a < b*c
disp('Hello world')
else
disp('Goodbye world')
end
Solution 3
b*c gives a value of 6, and 5 < 6, so this code will print 'Hello world'.
Exercise 4
Suppose the code in Exercise 2 is modified by adding parentheses around a > 0. What will it print?
a = 10;
if (a > 0)
disp('a is positive')
else
disp('a is not positive')
end
Solution 4
The parentheses around the relational expression a > 0 will not change its validity, so this code will print 'a is positive'.
Exercise 5
Suppose the code in Exercise 3 is modified by adding the parentheses shown below. What will it print?
a = 5;
b = 3;
c = 2;
if (a < b)*c
disp('Hello world')
else
disp('Goodbye world')
end
Solution 5
The parentheses in this expression change its meaning completely. First, a < b is evaluated, and since it is false for the given values of a and b, it evaluates to zero. The zero is than multiplied by c, giving a value of zero which is interpreted as false. So this code prints 'Goodbye world'.
Exercise 6
What will the following code print?
p1 = 3.14;
p2 = 3.14159;
if p1 == p2
disp('p1 and p2 are equal')
else
disp('p1 and p2 are not equal')
end
Solution 6
' p1 and p2 are not equal'
Exercise 7
What will the following code print?
a = 5;
b = 10;
if a = b
disp('a and b are equal')
else
disp('a and b are not equal')
end
Solution 7
This code will generate an error message, since a = b assigns the value of b to a. To check if a and b are equal, use a == b.
Exercise 8
For what values of the variable a will the following MATLAB code print 'Hello world'?
if ~ a == 0
disp('Hello world')
else
disp('Goodbye world')
end
Solution 8
Any value that is not zero.
Exercise 9
For what values of the variable a will the following code print 'Hello world'?
if a >= 0 && a < 7
disp('Hello world')
else
disp('Goodbye world')
end
Solution 9
Any value greater than or equal to 0 and less than 7.
Exercise 10
For what values of the variable a will the following code print 'Hello world'?
if a < 3 || a > 10
disp('Hello world')
else
disp('Goodbye world')
end
Solution 10
Any value less than 3 or greater than 10.
Exercise 11
For what values of the variable a will the following code print 'Hello world'?
if a < 7 || a >= 3
disp('Hello world')
else
disp('Goodbye world')
end
Solution 11
Every value of a will print 'Hello world'.
Exercise 12
Write an if statement that will print 'a is very close to zero' if the value of the variable a is between -0.01 and 0.01.
Solution 12
if a >= -0.01 && a <= 0.01
disp('a is very close to zero')
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Last edited by Darryl Morrell on Sep 21, 2006 4:32 pm GMT-5.