Tuesday, 19 October, 2021

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Contents

- 1. SymbolExplanation
- 2. Expression’s
- 3. Floating-point
- 4. Solution
- 5. Represents
- 6. Assignment
- 7. Currently

Table B-2 shows symbols that appear on their own and are valid in a variety of locations. Always empty bottom type for diverging functions _ “Ignored” pattern binding; also used to make integer literals readableTable B-3 shows symbols that appear in the context of a path through the module hierarchy to an item.

Trait::method(...) Disambiguating a method call by naming the trait that defines it type::method(...) Disambiguating a method call by naming the type for which it’s defined

SymbolExplanation T: U Generic parameter T constrained to types that implement UT: 'a Generic type T must outlive lifetime 'a (meaning the type cannot transitively contain any references with lifetimes shorter than 'a) T : 'static Generic type T contains no borrowed references other than 'static ones 'b: 'a Generic lifetime 'b must outlive lifetime 'at: ? Sized Allow generic type parameter to be a dynamically sized type 'a + trait, trait + trait Compound type constraintTable B-6 shows symbols that appear in the context of calling or defining macros and specifying attributes on an item. Macro invocationTable B-7 shows symbols that create comments.

*/ Inner block doc comment /**...*/ Outer block doc commendable B-8 shows symbols that appear in the context of using tuples. SymbolExplanation () Empty tuple (aka unit), both literal and type (exp) Parenthesized expression (exp, ) Single-element tuple expression (type, ) Single-element tuple type (exp, ...) Tuple expression (type, ...) Tuple type exp(exp, ...) Function call expression; also used to initialize tuple struct s and tuple ENIM variants exp.0, exp.1, etc. Tuple indefinable B-9 shows the contexts in which curly braces are used.

ContextExplanation {...} Block expression Type {...}struct literalTable B-10 shows the contexts in which square brackets are used. An operator defines some function that will be performed on the data.

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Sr. No Operator DescriptionExample1+(Addition)returns the sum of the operands+b is 152-(Subtraction)returns the difference of the values is 53* (Multiplication)returns the product of the valuesa×b is 504/ (Division)performs division operation and returns the quotient / b is 25% (Modulus)performs division operation and returns the remainder % b is 0 NOTE The ++ and -- operators are not supported in Rust. Relational Operators test or define the kind of relationship between two entities.

(NOT)The operator returns the inverse of the expression’s result. (A & B) is 22| (BitWise OR)It performs a Boolean OR operation on each bit of its integer arguments.

(A | B) is 33^ (Bitwise XOR)It performs a Boolean exclusive OR operation on each bit of its integer arguments. Shifting a value left by one position is equivalent to multiplying it by 2, shifting two positions is equivalent to multiplying by 4, and so on.

Image by the author. Python and Rust share the same arithmetic symbols as you see in the above table. In Rust, you can’t use different datatype in an operation.

All the integer types u8, u16, u32, u64, u128, i16, i32, i64, i128, size, and size have the pow method. The above definition tells you that using the pow method raises self to the power of exp (which is u32) and returns i32 (a signed integer).

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Powi raises a number to an integer power and pow raises a number to a floating-point power. Rust Floor Division method examples.

Rust uses the two’s complement to find the bitwise negation for signed types. Rust ’s signed integer types are called the signed two’s complement integer types.

Rust and Python Compound Assignment Operators Rust compound assignment examples. You can find Rust over loadable operators in the standard library ops module.

We are going to use this XOR to solve the Decoder problem called Single number. In this problem, an array input has a pair of numbers except one, for example .

You need to find a sing number from this array and in this case the output should be 2. We briefly go through the Python solution to see how the problem was solved.

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Line 3–4: After importing List, we create a class called Solution and method called singleNumber. Using a for loop, we iterate the input array, nuns using XOR compound assignment, ans ^= n.

We use a keyword struct and set fields with its type within the curly bracket. Line 2–4: Create a struct called Solution that takes one field nuns with DEC

Line 6–10: We create a method single_number in imply Solution. Line 12–17: In the main function, we create an instance and print 1 using the method.

Methods are defined within the context of a struct and their first parameter is always self, which represents the instance of the struct the method is being called on. Associated functions don’t take self as a parameter, and they are not methods because they don’t have an instance of the struct to work with.

We use the :: syntax with the struct name to call this associated function whereas we use. Rust final solution code. Line 7–11: We create a mutable variable and with the type of i32.

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Rust result in the Electrode Since we learned about the associated function, let’s apply it to this problem. This new function takes one parameter nuns that is a vector with items of i32.

In this problem, you input a non-negative integer sum and return the number of steps to reduce it to zero. If the modulus is 0, then it must be an even number, so we divide the sum by 2 using a compound assignment /=2, otherwise, we subtract 1 using a compound assignment -=1.

Line 7–16: We assign 0 to a mutable variable steps. While self.sum is greater than 0, we use the compound assignment /=2 if self.num's remainder is 0, otherwise, we subtract 1, and increase the number of step by 1.

Rust result from the Electrode We learned arithmetic, comparison, logical, bitwise, and compound assignment operators in Rust. We also learned operator overloading, the difference between associated function and methods, how to use operators in Rust by converting simple Python codes to Rust.

Note: this code could be made simpler with a single call to std::FS::read_to_string, but we're writing it all out manually here to have an example with multiple errors. This code has two paths that can fail, opening the file and reading the data from it.

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If either of these fail to work, we'd like to return an error from read_username_from_file. Doing so involves match ING on the result of the I/O operations.

If it was an Err, it returns from the function you're currently in. Character to indicate that here we are handling errors in the standard way, by passing them up the call stack.

The first is quite difficult to scan visually, and each layer of error handling prefixes the expression with an additional call to try! This brings undue attention to the trivial error propagation, obscuring the main code path, in this example the calls to foo, bar and BAZ.