Edge cases in the string vs. String comparison in C#

Whilst most C# developer would know that in C# the string type is equivalent to the System.String type because string is simply an alias for the System.String type. There are other framework defined alias like string, such as int for System.Int32 and long for System.Int64.

Whilst in normal usage the two are identical, thanks to Marc Gravell’s answer here, I found out about two interesting edge cases:

  • you need a  using System; to use String, you don’t for string
  • if you define a local class String { }, then String refers to that class, you can’t define a class called string

On a related topic, one thing that’s always been curious to me is that there are no ToInt or ToLong methods in the Convert class but only ToIn32 and ToInt64. Dan Puzey gave me a plausible explanation for this though:

Convert is a framework class, not a language keyword. If it had methods named after the C# keywords, the methods would make no sense in VB or F# or other .NET languages.

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Yan Cui

I’m an AWS Serverless Hero and the author of Production-Ready Serverless. I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.

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