From 180e650cb220ac27e8ca5f7827ab609078f591a5 Mon Sep 17 00:00:00 2001 From: Dominik Picheta Date: Thu, 5 Jun 2014 00:43:00 +0100 Subject: [PATCH] Create type_casting_inference.md --- content/variables/type_casting_inference.md | 35 +++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 content/variables/type_casting_inference.md diff --git a/content/variables/type_casting_inference.md b/content/variables/type_casting_inference.md new file mode 100644 index 0000000..7bd2544 --- /dev/null +++ b/content/variables/type_casting_inference.md @@ -0,0 +1,35 @@ +--- +title: Type casting and inference +--- +# Type casting and inference + +Nimrod is a statically typed language. As such, each variable has a type associated with it. As seen in the previous example these types are inferred in the `const`, `let` and `var` declarations by the compiler. + +```nimrod +# These types are inferred. +var x = 5 # int +var y = "foo" # string + +# Assigning a value of a different type will result in a compile-time error. +x = y +``` + +```console +$ nimrod c -r typeinference.nim +typeinference.nim(6, 4) Error: type mismatch: got (string) but expected 'int' +``` + +You may optionally specify the type after a colon (`:`). In some cases the compiler will expect you to explicitly cast types though. This can be done in two ways. One is to use "type conversion", this is the safe method, the compiler will ensure that it is safe to convert to that type. The other is to use the `cast` keyword, this is the unsafe method and should only be used when working with hardware or interfacing with C. + +```nimrod +var x: int = int(1 / 3) # Type conversion. `/` returns a Float. The `: int` is superfluous. + +var y = "Foobar" +proc ffi(foo: ptr array[6, char]) = echo repr(foo) +ffi(cast[ptr array[6, char]](addr y[0])) +``` + +```console +$ nimrod c -r typecasting.nim +ref 002C8030 --> ['F', 'o', 'o', 'b', 'a', 'r'] +```