title: Rust date: 2022-01-01 11:51:44 background: bg-black tags: categories: - Programming intro: |
fn main() {
println!("Hello, World!");
}
$ rustc Hello_World.rs
$ ./Hello_World
Hello, World!
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 {.wrap} // Single Placeholder println!("{}", 1);
// Multiple Placeholder println!("{} {}", 1, 3);
// Positional Arguments println!("{0} is {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");
// 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;
// Line Comments
/*.............Block Comments */
/// Outer doc comments
//! Inner doc comments
See: Comment
fn test(){
println!("This is a function!");
}
fn main(){
test();
}
See: Functions
let mut a: u32 = 8;
let b: u64 = 877;
let c: i64 = 8999;
let d = -90;
let mut sixty_bit_float: f64 = 89.90;
let thirty_two_bit_float: f32 = 7.90;
let just_a_float = 69.69;
```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}"; // => 😀
```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
let array: [i64; 6] = [92,97,98,99,98,94];
j0 j1 j2 j3 j4 j5
┌────┬────┬────┬────┬────┬────┐
i0 | 1 | 2 | 3 | 4 | 5 | 6 |
├────┼────┼────┼────┼────┼────┤
i1 | 6 | 5 | 4 | 3 | 2 | 1 |
└────┴────┴────┴────┴────┴────┘
let array: [[i64; 6] ;2] = [
[1,2,3,4,5,6],
[6,5,4,3,2,1]];
let mut array: [i32 ; 3] = [2,6,10];
array[1] = 4;
array[2] = 6;
Use the mut
keyword to make it mutable.
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:?}");
let some_vector = vec![1,2,3,4,5];
A vector is declared using the vec!
macro.
let tuple = (1, 'A' , "Cool", 78, true);
let cs:&str = "cheat sheet";
// => Share cheat sheet for developers
println!("Share {cs} for developers");
// 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}");
let rand = String::from("Random String");
rand.capacity() // => 13
Calculates the capacity of the string in bytes.
let name = String::from("ElementalX");
name.contains("Element") // => true
Checks if the substring is contained inside the original string or not.
let mut half_text = String::from("Hal");
half_text.push('f'); // => Half
let mut hi = String::from("Hey there...");
hi.push_str("How are you doing??");
// => Hey there...How are you doing??
println!("{hi}");
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 f |
e <= f |
e is less than or equal to f |
e >= f |
e is greater or equal to f |
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
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 ~ h` | 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
Example | Meaning |
---|---|
c && d |
Both are true (AND) |
c || d |
Either is true (OR) |
!c |
c is false (NOT) |
let (c, d) = (true, false);
let and = c && d; // => false
let or = c || d; // => true
let not = !c; // => false
let mut k = 9;
let mut l = k;
Operator | Description |
---|---|
k += l |
Add a value and assign, then k=9 |
k -= l |
Substrate a value and assign, then k=18 |
k /= l |
Divide a value and assign, then k=9 |
k *= l |
Multiply a value and assign, then k=81 |
k |= l |
Bitwise OR and assign, then k=89 |
let case1: i32 = 81;
let case2: i32 = 82;
if case1 < case2 {
println!("case1 is greater than case2");
}
let case3 = 8;
let case4 = 9;
if case3 >= case4 {
println!("case3 is better than case4");
} else {
println!("case4 is greater than case3");
}
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");
}
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");
}
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");
}
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!")
}
};
}
let nested_conditions = 89;
if nested_conditions == 89 {
let just_a_value = 98;
if just_a_value >= 97 {
println!("Greater than 97");
}
}
for mut i in 0..15 {
i-=1;
println!("The value of i is : {i}");
}
let mut check = 0;
while check < 11{
println!("Check is : {check}");
check+=1;
println!("After incrementing: {check}");
if check == 10{
break; // stop while
}
}
loop {
println!("hello world forever!");
}
The infinite loop indicated.
let mut i = 1;
loop {
println!("i is {i}");
if i > 100 {
break;
}
i *= 2;
}
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}"};
}
fn print_message(){
println!("Hello, QuickRef.ME!");
}
fn main(){
//Invoking a function in Rust.
print_message();
}
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
}
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
}
```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:?}");
}
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;
}
let a_int = 90; // int
// int to float
let mut type_cast = (a_int as f64);
let orginal: char = 'I';
// char to int => 73
let type_casted: i64 = orginal as i64;
To perform type-casting in Rust one must use the as
keyword.
let mut foo = 4;
let mut borrowed_foo = &foo;
println!("{borrowed_foo}");
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.
let mut borrow = 10;
let deref = &mut borrow;
println!("{}", *deref);
De-referencing in rust can be done using the *
operator
{
// 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