E0308 rust type_error ai_generated true

错误[E0308]：类型不匹配：期望 `usize`，得到 `f64`

error[E0308]: mismatched types: expected `usize`, found `f64`

ID: rust/e0308-expected-usize-found-float

其他格式: JSON · Markdown 中文 · English
92%修复率
88%置信度
1证据数
2023-06-15首次发现

版本兼容性

版本状态引入弃用备注
rustc 1.70.0 active — — —
rustc 1.75.0 active — — —
rustc 1.82.0 active — — —

根因分析

在需要无符号整数索引的位置（如数组索引或切片操作）使用了浮点数。

English

Assigning or passing a floating-point value where an unsigned integer index is required, often in array indexing or slice operations.

generic

官方文档

https://doc.rust-lang.org/error_codes/E0308.html

解决方案

  1. Use `as usize` to convert f64 to usize, ensuring the value is non-negative and within range: `let index = value as usize;`
  2. Use `f64::round()` or `f64::floor()` before casting: `let index = value.round() as usize;`
  3. If the value is from user input or computation, parse or compute it as `usize` directly: `let index: usize = some_usize_source;`

无效尝试

常见但无效的做法:

  1. 45% 失败

    Truncation may cause logic errors; the compiler allows it but the behavior is undefined for negative or NaN values.

  2. 100% 失败

    Rust requires explicit conversion; this approach is syntactically invalid.

  3. 60% 失败

    If the value comes from a computation or input that yields f64, the type mismatch persists.