---
title: Rust
date: 2022-01-01 11:51:44
background: bg-black
tags:
categories:
- Programming
intro: |
The Rust quick reference cheat sheet that aims at providing help on writing basic syntax and methods.
plugins:
- copyCode
---
## Getting Started
### Hello_World.rs
```rust
fn main() {
println!("Hello, World!");
}
```
#### Compiling and Running
```shell
$ rustc Hello_World.rs
$ ./Hello_World
Hello, World!
```
### Primitive types
| | |
| ------------------------- | :------------------------------ |
| `bool` | Boolean (`true` _/_ `false`) |
| `char` | character |
| `f32`, `f64` | 32-bits, 64-bits floats |
| `i64`, `i32`, `i16`, `i8` | signed 16- ... integers |
| `u64`, `u32`, `u16`, `u8` | unsigned 16-bits, ... integers |
| `isize` | pointer-sized signed integers |
| `usize` | pointer-sized unsigned integers |
See: [Rust Types](#rust-types)
### Formatting {.row-span-2}
```rust {.wrap}
// Single Placeholder
println!("{}", 1);
// Multiple Placeholder
println!("{} {}", 1, 3);
// Positional Arguments
println!(
"{0} is a {1} {2}, also {0} is a {3} programming language",
"Rust", "cool", "language", "safe"
);
// Named Arguments
println!(
"{country} is a diverse nation with unity.",
country = "India"
);
// Placeholder traits :b for binary, :0x is for hex and :o is octal
println!("Let us print 76 is binary which is {:b} , and hex equivalent is {:0x} and octal equivalent is {:o}", 76, 76, 76);
// Debug Trait
println!(
"Print whatever we want to here using debug trait {:?}",
(76, 'A', 90)
);
// New Format Strings in 1.58
let x = "world";
println!("Hello {x}!");
```
### Printing Styles
```rust
// Prints the output
print!("Hello World\n");
// Appends a new line after printing
println!("Appending a new line");
// Prints as an error
eprint!("This is an error\n");
// Prints as an error with new line
eprintln!("This is an error with new line");
```
### Variables
```rust
// Initializing and declaring a variable
let some_variable = "This_is_a_variable";
// Making a variable mutable
let mut mutable_variable = "Mutable";
// Assigning multiple variables
let (name, age) = ("ElementalX", 20);
// (Global) constant
const SCREAMING_SNAKE_CASE: i64 = 9;
```
### Comments
```rust
// Line Comments
/*.............Block Comments */
/// Outer doc comments
//! Inner doc comments
```
See: [Comment](https://doc.rust-lang.org/reference/comments.html)
### Functions
```rust
fn test() {
println!("This is a function!");
}
fn main() {
test();
}
```
See: [Functions](#rust-functions)
## Rust Types
### Integer
```rust
let mut a: u32 = 8;
let b: u64 = 877;
let c: i64 = 8999;
let d = -90;
```
### Floating-Point
```rust
let mut sixty_bit_float: f64 = 89.90;
let thirty_two_bit_float: f32 = 7.90;
let just_a_float = 69.69;
```
### Boolean
```rust {.wrap}
let true_val: bool = true;
let false_val: bool = false;
let just_a_bool = true;
let is_true = 8 < 5; // => false
```
### Character
```rust
let first_letter_of_alphabet = 'a';
let explicit_char: char = 'F';
let implicit_char = '8';
let emoji = "\u{1f600}"; // => 😀
```
### String Literal
```rust {.wrap}
let community_name = "AXIAL";
let no_of_members: &str = "ten";
println!("The name of the community is {community_name} and it has {no_of_members} members");
```
See: [Strings](#rust-strings)
### Arrays
```rust
┌─────┬─────┬─────┬─────┬─────┬─────┐
| 92 | 97 | 98 | 99 | 98 | 94 |
└─────┴─────┴─────┴─────┴─────┴─────┘
0 1 2 3 4 5
```
---
```rust
let array: [i64; 6] = [92, 97, 98, 99, 98, 94];
```
### Multi-Dimensional Array {.row-span-2}
```rust
j0 j1 j2 j3 j4 j5
┌────┬────┬────┬────┬────┬────┐
i0 | 1 | 2 | 3 | 4 | 5 | 6 |
├────┼────┼────┼────┼────┼────┤
i1 | 6 | 5 | 4 | 3 | 2 | 1 |
└────┴────┴────┴────┴────┴────┘
```
---
```rust
let array: [[i64; 6]; 2] = [
[1, 2, 3, 4, 5, 6],
[6, 5, 4, 3, 2, 1]
];
```
### Mutable Array
```rust
let mut array: [i32; 3] = [2, 6, 10];
array[1] = 4;
array[2] = 6;
```
Use the `mut` keyword to make it mutable.
### Slices
```rust
let mut array: [i64; 4] = [1, 2, 3, 4];
let mut slices: &[i64] = &array[0..3]; // Lower range is inclusive and upper range is exclusive
println!("The elements of the slices are : {slices:?}");
```
### Vectors
```rust
let some_vector = vec![1, 2, 3, 4, 5];
```
A vector is declared using the `vec!` macro.
### Tuples
```rust
let tuple = (1, 'A', "Cool", 78, true);
```
## Rust Strings
### String Literal
```rust
let cs: &str = "cheat sheet";
// => Share cheat sheet for developers
println!("Share {cs} for developers");
```
### String Object
```rust
// Creating an empty string object
let my_string = String::new();
// Converting to a string object
let S_string = a_string.to_string();
// Creating an initialized string object
let lang = String::from("Rust");
println!("First language is {lang}");
```
### .capacity()
```rust
let rand = String::from("Random String");
rand.capacity() // => 13
```
Calculates the capacity of the string in bytes.
### .contains()
```rust
let name = String::from("ElementalX");
name.contains("Element") // => true
```
Checks if the substring is contained inside the original string or not.
### Pushing a single character
```rust
let mut half_text = String::from("Hal");
half_text.push('f'); // => Half
```
### Pushing an entire String
```rust
let mut hi = String::from("Hey there...");
hi.push_str("How are you doing??");
// => Hey there...How are you doing??
println!("{hi}");
```
## Rust Operators
### Comparison Operators
| | |
| -------- | :------------------------------- |
| `e == f` | `e` is equal to `f` |
| `e != f` | `e` is NOT equal to `f` |
| `e < f` | `e` is less than `f` |
| `e > f` | `e` is greater than `f` |
| `e <= f` | `e` is less than or equal to `f` |
| `e >= f` | `e` is greater or equal to `f` |
---
```rust
let (e, f) = (1, 100);
let greater = f > e; // => true
let less = f < e; // => false
let greater_equal = f >= e; // => true
let less_equal = e <= f; // => true
let equal_to = e == f; // => false
let not_equal_to = e != f; // => true
```
### Arithmetic Operators
| | |
| -------- | :----------------------------------------- |
| `a + b` | `a` is added to `b` |
| `a - b` | `b` is subtracted from `a` |
| `a / b` | `a` is divided by `b` |
| `a % b` | Gets remainder of `a` by dividing with `b` |
| `a * b` | `a` is multiplied with `b` |
---
```rust {.wrap}
let (a, b) = (4, 5);
let sum: i32 = a + b; // => 9
let subtractions: i32 = a - b; // => -1
let multiplication: i32 = a * b; // => 20
let division: i32 = a / b; // => 0
let modulus: i32 = a % b; // => 4
```
### Bitwise Operators
| Operator | Description |
| ------------------- | ----------------------- |
| `g & h` | Binary AND |
| g \| h | Binary OR |
| `g ^ h` | Binary XOR |
| `!g` | Binary one's complement |
| `g << h` | Binary shift left |
| `g >> h` | Binary shift right |
---
```rust {.wrap}
let (g, h) = (0x1, 0x2);
let bitwise_and = g & h; // => 0
let bitwise_or = g | h; // => 3
let bitwise_xor = g ^ h; // => 3
let right_shift = g >> 2; // => 0
let left_shift = h << 4; // => 32
```
### Logical Operators
| Example | Meaning |
| --------------------- | --------------------- |
| `c && d` | Both are true _(AND)_ |
| c \|\| d | Either is true _(OR)_ |
| `!c` | `c` is false _(NOT)_ |
---
```rust
let (c, d) = (true, false);
let and = c && d; // => false
let or = c || d; // => true
let not = !c; // => false
```
### Compound Assignment Operator
```rust
let mut k = 9;
let mut l = k;
```
---
| Operator | Description |
| -------------------- | --------------------------------------- |
| `k += l` | Add a value and assign, then k=18 |
| `k -= l` | Subtract a value and assign, then k=0 |
| `k /= l` | Divide a value and assign, then k=1 |
| `k *= l` | Multiply a value and assign, then k=81 |
| k \|= l | Bitwise OR and assign, then k=89 |
## Rust Flow Control
### If Expression
```rust
let case1: i32 = 81;
let case2: i32 = 82;
if case1 < case2 {
println!("case1 is less than case2");
}
```
### If...Else Expression
```rust
let case3 = 8;
let case4 = 9;
if case3 >= case4 {
println!("case3 is better than case4");
} else {
println!("case4 is greater than case3");
}
```
### If...Else...if...Else Expression
```rust
let foo = 12;
let bar = 13;
if foo == bar {
println!("foo is equal to bar");
} else if foo < bar {
println!("foo less than bar");
} else if foo != bar {
println!("foo is not equal to bar");
} else {
println!("Nothing");
}
```
### If...Let Expression {.row-span-3}
```rust
let mut arr1: [i64; 3] = [1, 2, 3];
if let [1, 2, _] = arr1 {
println!("Works with array");
}
let mut arr2: [&str; 2] = ["one", "two"];
if let ["Apple", _] = arr2 {
println!("Works with str array too");
}
```
---
```rust
let tuple_1 = ("India", 7, 90, 90.432);
if let (_, 7, 9, 78.99) = tuple_1 {
println!("Works with tuples too");
}
let tuple_2 = (9, 7, 89, 12, "Okay");
if let (9, 7, 89, 12, blank) = tuple_2 {
println!("Everything {blank} mate?");
}
let tuple_3 = (89, 90, "Yes");
if let (9, 89, "Yes") = tuple_3 {
println!("Pattern did match");
} else {
println!("Pattern did not match");
}
```
### Match Expression {.row-span-3}
```rust
let day_of_week = 2;
match day_of_week {
1 => {
println!("Its Monday my dudes");
}
2 => {
println!("It's Tuesday my dudes");
}
3 => {
println!("It's Wednesday my dudes");
}
4 => {
println!("It's Thursday my dudes");
}
5 => {
println!("It's Friday my dudes");
}
6 => {
println!("It's Saturday my dudes");
}
7 => {
println!("It's Sunday my dudes");
}
_ => {
println!("Default!")
}
};
```
### Nested...If Expression
```rust
let nested_conditions = 89;
if nested_conditions == 89 {
let just_a_value = 98;
if just_a_value >= 97 {
println!("Greater than 97");
}
}
```
### For Loop
```rust
for mut i in 0..15 {
i -= 1;
println!("The value of i is : {i}");
}
```
### While Loop
```rust
let mut check = 0;
while check < 11 {
println!("Check is : {check}");
check += 1;
println!("After incrementing: {check}");
if check == 10 {
break; // stop while
}
}
```
### Loop keyword
```rust
loop {
println!("hello world forever!");
}
```
The infinite loop indicated.
### Break Statement
```rust
let mut i = 1;
loop {
println!("i is {i}");
if i > 100 {
break;
}
i *= 2;
}
```
### Continue Statement
```rust
for (v, c) in (0..10 + 1).enumerate() {
println!("The {c} number loop");
if v == 9 {
println!("Here we go continue?");
continue;
}
println!("The value of v is : {v}");
}
```
## Rust Functions
### Basic function
```rust
fn print_message() {
println!("Hello, CheatSheets.zip!");
}
fn main() {
//Invoking a function in Rust.
print_message();
}
```
### Pass by Value
```rust
fn main() {
let x: u32 = 10;
let y: u32 = 20;
// => 200
println!("Calc: {}", cal_rect(x, y));
}
fn cal_rect(x: u32, y: u32) -> u32 {
x * y
}
```
### Pass by Reference
```rust
fn main() {
let mut by_ref = 3; // => 3
power_of_three(&mut by_ref);
println!("{by_ref}"); // => 9
}
fn power_of_three(by_ref: &mut i32) {
// de-referencing is important
*by_ref = *by_ref * *by_ref;
println!("{by_ref}"); // => 9
}
```
### Returns
```rust {.wrap}
fn main() {
let (mut radius, mut pi) = (3.0, 3.14);
let (area, _perimeter) = calculate(
&mut radius,
&mut pi
);
println!("The area and the perimeter of the circle are: {area} & {_perimeter}");
}
fn calculate(radius: &mut f64, pi: &mut f64) -> (f64, f64) {
let perimeter = 2.0 * *pi * *radius;
let area = *pi * *radius * *radius;
return (area, perimeter);
}
```
### Arrays as Arguments
```rust
fn main() {
let mut array: [i32; 5] = [1, 2, 3, 4, 6];
print_arrays(array);
println!("The elements: {array:?}");
}
fn print_arrays(mut array: [i32; 5]) {
array[0] = 89;
array[1] = 90;
array[2] = 91;
array[3] = 92;
array[4] = 93;
println!("The elements: {array:?}");
}
```
### Returning Arrays
```rust
fn main() {
let mut arr: [i32; 5] = [2, 4, 6, 8, 10];
multiply(arr);
println!("The array is : {:?}", multiply(arr));
}
fn multiply(mut arr: [i32; 5]) -> [i32; 5] {
arr[2] = 90;
for mut i in 0..5 {
arr[i] = arr[i] * arr[2];
}
return arr;
}
```
## Misc
### Type Casting
```rust
let a_int = 90; // int
// int to float
let mut type_cast = (a_int as f64);
```
---
```rust
let original: char = 'I';
// char to int => 73
let type_casted: i64 = original as i64;
```
To perform type-casting in Rust one must use the `as` keyword.
### Borrowing
```rust
let mut foo = 4;
let mut borrowed_foo = &foo;
println!("{borrowed_foo}");
```
---
```rust
let mut bar = 3;
let mut mutable_borrowed_bar = &mut bar;
println!("{mutable_borrowed_bar}");
```
Here borrowed value borrows the value from value one using `&` operator.
### De-referencing
```rust
let mut borrow = 10;
let deref = &mut borrow;
println!("{}", *deref);
```
De-referencing in rust can be done using the `*` operator
### Variable Scope
```rust
{
// The scope limited to this braces
let a_number = 1;
}
println!("{a_number}");
```
This will produce error as the scope of the variable `a_number` ends at the braces
## Also see
- [The Rust Document](https://doc.rust-lang.org/book/ch00-00-introduction.html) _(doc.rust-lang.org)_
- [The Rust Reference](https://doc.rust-lang.org/reference/introduction.html) _(doc.rust-lang.org)_
- [Rust Cheatsheet](https://phaiax.github.io/rust-cheatsheet/) _(phaiax.github.io)_