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You can describe any programming
concept with pseudo code.

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I'll show you how to describe two
programming control structures, loops and

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functions, using
easy-to-understand language.

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I'll start with loops in this video and
continue with functions in the next.

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If you want to follow along, open the
workspace associated with this video and

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the file named gpa.txt.

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Given a list of student grades,
calculate their GPA.

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The grading scale used should be 1 to 4.

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If any grade isn't a 1, 2, 3, or 4,
print a message and stop the program.

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Say you're creating a GPA calculator
that takes a student's grades and

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determines their overall
grade point average.

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First, we need to get the students grades.

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You might not know exactly how
that's going to be performed.

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Maybe those grades are manually input or

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they're retrieved from a database or
they exist somewhere else.

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The nice thing about pseudo code is that
it can describe just what needs to happen,

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not exactly how.

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When you sit down to program,
you'll need to figure out that part.

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But when you are first working through
the logic, you could just write retrieve

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student_grades to capture what
you'll need to program eventually.

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You also need a variable to store
the total value of the grades,

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set grade_total to 0 does that.

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To get the total value for the grades,
you should add them all up.

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Looping through the collection of
grades one at a time will do the trick.

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So for
each grade in the grades collection,

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the program will add that grade
to the grade_total variable.

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The requirements say we need to check
if the grade is a valid number.

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So I'll add a conditional statement.

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Notice that I've indented the conditional
statement because it's inside the loop.

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I'll also indent again inside
the conditional statement,

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to show these steps take place when
the grade isn't a valid number,

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print out a few messages,
then stop the loop.

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If the grade is valid,
then it's added to the grade_total.

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Once the loop is done,
there's just two more steps.

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Calculate the grade point average
by dividing the grade_total

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by the number of grades,
then print out the gpa.

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This pseudo code seems to match all
of the requirements for the project.

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In reviewing it,

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I realize that this program would
probably work better as a function,

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a collection of programming steps that
you can reuse over and over again.

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In the next video, I'll convert
this example to use a function.