Скачать или смотреть How to Efficiently Count and Compare Numbers in DataGridView Using C#

Learn how to resolve data comparison issues in C# WinForms `DataGridView` by counting occurrences and summing values seamlessly.
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How to Efficiently Count and Compare Numbers in DataGridView Using C#

Working with data in DataGridView can be a common requirement in C# WinForms applications, especially when you need to calculate metrics or count occurrences based on specific criteria. In this guide, we'll address a scenario where you need to count the instances of "hard work" based on a time threshold. Specifically, we'll resolve an issue where the application throws an error when trying to perform a comparison on a value in the "TotalTime" column. Let’s break down how to handle this efficiently.

Understanding the Problem

You have a DataGridView displaying workload data, and you aim to count how many entries meet a certain time threshold ( = 30) while also summing total time worked. The error message "specified cast is not valid" generally indicates that the data type you are trying to convert or parse does not match the expected type. This common pitfall can lead to frustration, especially when working with dynamic data types in a grid view.

Solution Overview

We'll revise your code to ensure the counting and summing operations are handled smoothly without throwing an exception. Here’s a clean, effective approach to achieve this:

Step 1: Initialize Counters

First, we need to initialize two counters: one for counting the occurrences of hard work and another for summing the total time worked.

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Step 2: Loop Through Each Row

We can achieve the counting and summing in a single loop through the DataGridView rows. Here’s how we can do it:

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In this loop:

We access each cell in the "TotalTime" column.

We parse the value as a double to prevent casting errors.

We keep track of how many times the threshold is met while simultaneously summing the total time.

Step 3: Update the Labels

After the loop completes, we simply update the labels to show the results:

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Complete Code Example

Here’s how your BtnSearch_Click method might look after these adjustments:

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Conclusion

In summary, handling data in a DataGridView can be tricky given the dynamic nature of user inputs. By methodically checking your data types, managing exceptions, and streamlining your calculations, you can improve the reliability of your application. Use the outlined approach to enhance your application's performance and user experience while avoiding common pitfalls like specified casting errors. Don't let data types bog you down; with a little attention to detail, you can achieve efficient data handling!