Print Macros

| Macro | Newline | Use case |

|-------|---------|----------|

| `println!(fmt, …)` | Yes | Most common — print + newline |

| `print!(fmt, …)` | No | Print without newline |

| `eprintln!(fmt, …)` | Yes | Print to stderr |

| `format!(fmt, …)` | — | Build a `String` (no print) |

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Placeholders

| Placeholder | Meaning |

|-------------|---------|

| `{}` | Default display |

| `{:?}` | Debug output |

| `{:#?}` | Pretty-print debug |

| `{:.2}` | Float with 2 decimal places |

| `{:>10}` | Right-align in 10 chars |

| `{:<10}` | Left-align in 10 chars |

| `{:^10}` | Center in 10 chars |

| `{:0>5}` | Zero-pad to 5 chars |

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Named and Positional Arguments

```rust

let name = "Alice";

let age = 30;

println!("{name} is {age} years old"); // Rust 1.58+

println!("{0} is {1} years old", name, age); // positional

```

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Debug Formatting

Any type that derives `Debug` can be printed with `{:?}`:

```rust

let point = (1, 2, 3);

println!("{:?}", point); // (1, 2, 3)

println!("{:#?}", point); // pretty-printed

```

---

Number Formatting

```rust

let result = 22.0_f64 / 7.0;

println!("{:.2}", result); // 3.14

println!("{:.4}", result); // 3.1429

println!("{:08.2}", result); // 00003.14 (zero-padded width 8)

```

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Padding and Alignment

```rust

println!("{:<10}", "left"); // "left "

println!("{:>10}", "right"); // " right"

println!("{:^10}", "center"); // " center "

println!("{:-^10}", "hi"); // "----hi----"

```

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What's Next?

You can now format Rust output precisely. Next: **control flow** — if/else, match expressions, and pattern matching.