Looping through characters in a string in VB.NET

Question

I'm busy working on past exam papers in preparation for a Visual Basic exam. I need help with the following question which I'm stuck with.

Write a function procedure to calculate the number of times the characters "e", "f" and "g" appears in a string

I tried to write the psuedo code and came up with the following.

Loop through each individual character in the string
If the character = "e","f" or "g" add 1 to number of characters
Exit loop 
Display total in messagebox

How do I loop through individual characters in a string (using a for loop) and how do I count the number of times a specific character appears in a string?

Answer 1

The answer greatly depends on what you’ve already learned in your course work and which functions you are supposed to use.

But in general, looping over the characters in a string is as easy as this:

Dim s As String = "test"

For Each c As Char in s
    ' Count c
Next

As for counting, simply have separate counter variables (eCount As Integer etc.) for each character and increment them when c equals that character – obviously that approach doesn’t scale well once you increase the number of characters to count. This can be solved by maintaining a dictionary of the relevant characters but I’m guessing that this is too advanced for your exercise.