mirror of
https://github.com/chubin/cheat.sheets
synced 2024-11-01 21:40:24 +00:00
86 lines
2.3 KiB
Plaintext
86 lines
2.3 KiB
Plaintext
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// Functions
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// `i32` is the type for 32-bit signed integers
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fn add2(x: i32, y: i32) -> i32 {
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// Implicit return (no semicolon)
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x + y
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}
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// Main function
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fn main() {
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// Numbers //
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//
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// Immutable bindings
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let x: i32 = 1;
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// Integer/float suffixes
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let y: i32 = 13i32;
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let f: f64 = 1.3f64;
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// Type inference
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// Most of the time, the Rust compiler can infer what type a variable is, so
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// you don’t have to write an explicit type annotation.
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// Throughout this tutorial, types are explicitly annotated in many places,
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// but only for demonstrative purposes. Type inference can handle this for
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// you most of the time.
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let implicit_x = 1;
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let implicit_f = 1.3;
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// Arithmetic
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let sum = x + y + 13;
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// Mutable variable
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let mut mutable = 1;
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mutable = 4;
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mutable += 2;
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// Strings //
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//
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// String literals
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let x: &str = "hello world!";
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//
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// Printing
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println!("{} {}", f, x); // 1.3 hello world
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//
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// A `String` – a heap-allocated string
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let s: String = "hello world".to_string();
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//
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// A string slice – an immutable view into another string
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// This is basically an immutable pair of pointers to a string – it doesn’t
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// actually contain the contents of a string, just a pointer to
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// the begin and a pointer to the end of a string buffer,
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// statically allocated or contained in another object (in this case, `s`)
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let s_slice: &str = &s;
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//
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println!("{} {}", s, s_slice); // hello world hello world
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// Vectors/arrays //
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//
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// A fixed-size array
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let four_ints: [i32; 4] = [1, 2, 3, 4];
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//
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// A dynamic array (vector)
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let mut vector: Vec<i32> = vec![1, 2, 3, 4];
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vector.push(5);
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//
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// A slice – an immutable view into a vector or array
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// This is much like a string slice, but for vectors
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let slice: &[i32] = &vector;
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//
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// Use `{:?}` to print something debug-style
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println!("{:?} {:?}", vector, slice); // [1, 2, 3, 4, 5] [1, 2, 3, 4, 5]
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// Tuples //
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//
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// A tuple is a fixed-size set of values of possibly different types
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let x: (i32, &str, f64) = (1, "hello", 3.4);
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//
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// Destructuring `let`
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let (a, b, c) = x;
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println!("{} {} {}", a, b, c); // 1 hello 3.4
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//
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// Indexing
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println!("{}", x.1); // hello
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}
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