42i32

42i32 is a numeric literal used in the Rust programming language. It represents the value 42 with an explicit type suffix i32, ensuring that the literal has the 32-bit signed integer type regardless of type inference.

In Rust, i32 denotes a 32-bit signed integer. Therefore, the expression 42i32 has the value 42 as an i32. This can be assigned or used in expressions like let a = 42i32; or let b: i32 = 42i32;. The suffix affects how the compiler treats the literal, particularly in contexts where the exact type matters for operations or trait implementations.

The i32 type is defined to be 32-bit on all supported targets, with a typical range from -2147483648 to 2147483647. Using the i32 suffix guarantees that the literal is not inferred as a different integer type, which can be important for type safety and performance considerations in generic code.

Suffix notation for numeric literals is not universal across programming languages. While 42i32 is valid in Rust, other languages may use different syntax or no suffix at all for literals. The presence of an explicit type suffix like i32 helps developers convey intent and resolves type ambiguity in Rust code.

See also: i32 type, Rust numeric literals, integer literal suffixes.