Producing a value from some other value is a very common pattern and one that switch is often used for. Unfortunately using switch statements directly involve declaring the variable then setting it and breaking inside each case is verbose and error-prone.

This can be somewhat mitigated by simply wrapping the switch statement in a method of its own so you can take full advantage of the return keyword from each case thus avoiding the need to declare and set the variable and do away with all break statements.

In C# 8 this is no longer necessary as the expression form of switch to allow values to be emitted directly without wrapping them in a new function.

Code

Now

var sysInfo = new SysInfo();
GetNativeSystemInfo(ref sysInfo);

var procArch = sysInfo.ProcessorArchitecture switch
{
    0 => "x86",
    6 => "IA64",
    9 => "x64",
    _ => string.Empty;
};

Before

var sysInfo = new SysInfo();
GetNativeSystemInfo(ref sysInfo);

var procArch = GetPlatform(sysInfo);

string GetPlatform(SystemInfo sysInfo)
{
    switch (sysInfo.ProcessorArchitecture)
    {
        case 0: return "x86";
        case 6: return "IA64";
        case 9: return "x64";
        default: return string.Empty;
    }
}

More information

• What's new in C# 8.0