How to modify the app.config configuration file in C#?

In C#, the app.config configuration file can be modified using the following steps:

1. Open the app.config file in the Visual Studio project.
2. Locate the configuration items that need to be modified in the file, such as:

<appSettings>
  <add key="SomeSetting" value="SomeValue" />
</appSettings>

1. Change the value of the configuration item, for example, modify SomeValue to NewValue:

<appSettings>
  <add key="SomeSetting" value="NewValue" />
</appSettings>

1. Save the files and rebuild the project.
2. Use the ConfigurationManager class in the code to read and modify configuration values, for example:

string settingValue = ConfigurationManager.AppSettings["SomeSetting"];
Console.WriteLine(settingValue);

By following the above steps, you can modify the configuration parameter values in the app.config file in C#.