Question

I’m new to the C# world and I can’t find a method to declare read only variable in C# (something like declaring “const” variable in c++). Is there one?

I’ll give you an example:

...
int f() { return x; } // x is not const member
...
void g() {
    int readOnlyVar = f(); // is there a method to declare readOnlyVar as read only or const

    // Some code in which I want to restrict access to readOnlyVar to read only 
}

Answer 1

There isn’t an identical analogue.

The readonly keyword allows the variable value to be mutated, but only in a constructor.

The const keyword means the value cannot mutate and needs to be a compile time constant and can only be one of the following types: sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal, bool, string, an enum-type, or a reference-type. (C# 4.0 spec §10.4).

And in c#, readonly only applies to fields and cannot be applied to local variables.