When to Use int vs Int32 or string vs String in C#

c++types

In C#, the keywords for built-in types are simply aliases for corresponding types in the System namespace.

Generally, it makes no difference whether you use a keyword (such as int) or an identifier (such as Int32) to refer to a built-in type. But there's an exception to everything, so my question in two parts is:

When does C# require you to use, or not use, a keyword?
When does using a keyword instead of an identifier change the meaning of the program?

Best Answer

C# doesn't require you to use one or the other as they are equivalent. It is a personal preference and coding convention. So use the one that seems more readable to you and your team. Just one advice: be consistent: do not use an alias in half of your codebase and the full type name in the second half.

Related Solutions

System.Convert.ToInt vs (int) in C# – Key Differences

Casting to int is implicit truncation, not implicit flooring:

double d = -3.14;
int i = (int)d;
// i == -3

I choose Math.Floor or Math.Round to make my intentions more explicit.

C# Type Conversion – Difference Between Convert.ToInt32 and (int)

(int)foo is simply a cast to the Int32 (int in C#) type. This is built into the CLR and requires that foo be a numeric variable (e.g. float, long, etc.) In this sense, it is very similar to a cast in C.

Convert.ToInt32 is designed to be a general conversion function. It does a good deal more than casting; namely, it can convert from any primitive type to a int (most notably, parsing a string). You can see the full list of overloads for this method here on MSDN.

And as Stefan Steiger mentions in a comment:

Also, note that on a numerical level, (int) foo truncates foo (ifoo = Math.Floor(foo)), while Convert.ToInt32(foo) uses half to even rounding (rounds x.5 to the nearest EVEN integer, meaning ifoo = Math.Round(foo)). The result is thus not just implementation-wise, but also numerically not the same.

Best Answer

Related Solutions

System.Convert.ToInt vs (int) in C# – Key Differences

C# Type Conversion – Difference Between Convert.ToInt32 and (int)

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