循环通过VB.NET中的字符串中的字符 [英] Looping through characters in a string in VB.NET

问题描述

我正忙于处理过去的考试文件，以准备Visual Basic考试。我需要帮助下面的问题，我被困住。

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.

编写函数过程来计算字符e，f和g出现在字符串中的次数

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

我试着写出伪代码，并得出以下结果。

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

如何循环字符串中的单个字符code> for loop）和如何计算特定字符出现在字符串中的次数？

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?

推荐答案

答案很大程度上取决于你在课程中学到的内容，以及你应该使用哪些函数。

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

循环字符串中的字符就像这样：

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

对于计数，对于每个字符只需要单独的计数器变量（ eCount As Integer 等），并在 c 等于该字符 - 显然，一旦增加要计数的字符数，该方法就不会很好地缩放。这可以通过维护相关字符的字典来解决，但我猜测这对你的练习来说太先进了。

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.

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