Table of Contents
C++ auto Keyword
In C++, the `auto` keyword is used for type inference during variable declaration. It allows the compiler to deduce the type of a variable from its initializer expression. Here's a code example:
```cpp auto x = 42; // x is deduced as an int ```
Python Equivalent: Dynamic Typing
In Python, there's no direct equivalent to C++'s `auto` because Python is dynamically typed. Variable types are determined at runtime, so there's no need for explicit type inference. Here's an example:
```python x = 42 # x is dynamically typed as an integer ```
Java Equivalent: var Keyword
In Java, the `var` keyword was introduced in Java 10 to allow local variable type inference. It's similar to C++'s `auto` but is more limited in its use. Here's how it's used:
```java var x = 42; // x is inferred as an int ```
C# Equivalent: var Keyword
In C#, the `var` keyword is used for type inference, allowing the compiler to determine the type of a variable based on the assigned value. Here's an example:
```csharp var x = 42; // x is inferred as an int ```
Kotlin Equivalent: val Keyword
In Kotlin, the `val` keyword is used for immutable variables with type inference. It's similar to C++'s `auto` but emphasizes immutability. Here's an example:
```kotlin val x = 42 // x is inferred as an Int ```
JavaScript and TypeScript Equivalent: const and let Keywords
In JavaScript and TypeScript, variable declarations can use `const`, `let`, or `var` keywords. While not directly equivalent to C++'s `auto`, they offer similar flexibility in variable typing. Here's an example:
```javascript const x = 42; // x is constant and inferred as a number ```
In TypeScript, type inference can also be achieved using `let` or `const`:
```typescript const x = 42; // x is inferred as number ```
https://developer.mozilla.org/en-US/docs/Web/JavaScript https://www.typescriptlang.org/docs/
PHP Equivalent: No Direct Equivalent
PHP is dynamically typed like Python, so there's no direct equivalent to C++'s `auto`. Variable types are determined at runtime.
Go Equivalent: Short Variable Declaration
In Go, the `:=` operator is used for variable declaration and assignment with type inference. It's similar to C++'s `auto` in that it infers the type of the variable from the assigned value. Here's an example:
```go x := 42 // x is inferred as an int ```
Rust Equivalent: let Keyword
In Rust, the `let` keyword is used for variable declaration and pattern matching. While not exactly equivalent to C++'s `auto`, it allows for type inference. Here's an example:
```rust let x = 42; // x is inferred as an i32 (32-bit signed integer) ```
Swift Equivalent: Type Inference
In Swift, type inference is used extensively to deduce the type of variables. There's no explicit keyword like C++'s `auto`, but the compiler automatically infers types based on the assigned values. Here's an example:
```swift let x = 42 // x is inferred as an Int ```
https://docs.swift.org/swift-book/LanguageGuide/TheBasics.html
Transact-SQL Equivalent: No Direct Equivalent
In Transact-SQL (T-SQL), there's no direct equivalent to C++'s `auto`. However, dynamic SQL allows for executing SQL statements dynamically at runtime, providing some level of flexibility similar to type inference. Here's an example:
```sql DECLARE @x INT; SET @x = 42; – @x is inferred as an int ```
https://docs.microsoft.com/en-us/sql/t-sql/language-reference?view=sql-server-ver15
PL/SQL Equivalent: No Direct Equivalent
PL/SQL is statically typed, and variable types need to be explicitly declared. There's no direct equivalent to C++'s `auto` in PL/SQL.