$ rustc HeadAndTail.rs error[E0425]: cannot find value `Utils` in this scope --> HeadAndTail.rs:13:14 | 13 | maxLines = Utils.stoiWithDefault(args[1], 10); | ^^^^^ not found in this scope error[E0308]: mismatched types --> HeadAndTail.rs:16:50 | 16 | let mut buffer:Vec<String> = Vec::with_capacity(maxLines); | ------------------ ^^^^^^^^ expected `usize`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/alloc/src/vec/mod.rs:478:12 help: you can convert an `isize` to a `usize` and panic if the converted value doesn't fit | 16 | let mut buffer:Vec<String> = Vec::with_capacity(maxLines.try_into().unwrap()); | ++++++++++++++++++++ error[E0425]: cannot find function `getline` in this scope --> HeadAndTail.rs:19:8 | 19 | while getline(line) { | ^^^^^^^ not found in this scope error[E0277]: the type `[String]` cannot be indexed by `isize` --> HeadAndTail.rs:20:10 | 20 | buffer[count % maxLines] = String::from(line); | ^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize` | = help: the trait `SliceIndex<[String]>` is not implemented for `isize` = help: the trait `SliceIndex<[T]>` is implemented for `usize` = note: required for `Vec<String>` to implement `Index<isize>` error[E0277]: the type `[String]` cannot be indexed by `isize` --> HeadAndTail.rs:31:27 | 31 | println!("{}", buffer[i]); | ^ slice indices are of type `usize` or ranges of `usize` | = help: the trait `SliceIndex<[String]>` is not implemented for `isize` = help: the trait `SliceIndex<[T]>` is implemented for `usize` = note: required for `Vec<String>` to implement `Index<isize>` error[E0277]: the type `[String]` cannot be indexed by `isize` --> HeadAndTail.rs:40:27 | 40 | println!("{}", buffer[(count + i) % maxLines]); | ^^^^^^^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize` | = help: the trait `SliceIndex<[String]>` is not implemented for `isize` = help: the trait `SliceIndex<[T]>` is implemented for `usize` = note: required for `Vec<String>` to implement `Index<isize>` error: aborting due to 6 previous errors Some errors have detailed explanations: E0277, E0308, E0425. For more information about an error, try `rustc --explain E0277`. $ rustc HeadAndTail.rs error[E0425]: cannot find value `Utils` in this scope --> HeadAndTail.rs:13:14 | 13 | maxLines = Utils.stoiWithDefault(args[1], 10); | ^^^^^ not found in this scope error[E0308]: mismatched types --> HeadAndTail.rs:16:50 | 16 | let mut buffer:Vec<String> = Vec::with_capacity(maxLines); | ------------------ ^^^^^^^^ expected `usize`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/alloc/src/vec/mod.rs:478:12 help: you can convert an `isize` to a `usize` and panic if the converted value doesn't fit | 16 | let mut buffer:Vec<String> = Vec::with_capacity(maxLines.try_into().unwrap()); | ++++++++++++++++++++ error[E0425]: cannot find function `getline` in this scope --> HeadAndTail.rs:19:8 | 19 | while getline(line) { | ^^^^^^^ not found in this scope error[E0277]: the type `[String]` cannot be indexed by `isize` --> HeadAndTail.rs:20:10 | 20 | buffer[count % maxLines] = String::from(line); | ^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize` | = help: the trait `SliceIndex<[String]>` is not implemented for `isize` = help: the trait `SliceIndex<[T]>` is implemented for `usize` = note: required for `Vec<String>` to implement `Index<isize>` error[E0277]: the type `[String]` cannot be indexed by `isize` --> HeadAndTail.rs:31:27 | 31 | println!("{}", buffer[i]); | ^ slice indices are of type `usize` or ranges of `usize` | = help: the trait `SliceIndex<[String]>` is not implemented for `isize` = help: the trait `SliceIndex<[T]>` is implemented for `usize` = note: required for `Vec<String>` to implement `Index<isize>` error[E0277]: the type `[String]` cannot be indexed by `isize` --> HeadAndTail.rs:40:27 | 40 | println!("{}", buffer[(count + i) % maxLines]); | ^^^^^^^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize` | = help: the trait `SliceIndex<[String]>` is not implemented for `isize` = help: the trait `SliceIndex<[T]>` is implemented for `usize` = note: required for `Vec<String>` to implement `Index<isize>` error: aborting due to 6 previous errors Some errors have detailed explanations: E0277, E0308, E0425. For more information about an error, try `rustc --explain E0277`.