43 lines
964 B
Markdown
43 lines
964 B
Markdown
|
`if` Statement
|
||
|
|
==============
|
||
|
|
|
||
|
|
{{#include ../links.md}}
|
||
|
|
|
||
|
|
```rust
|
||
|
|
if foo(x) {
|
||
|
|
print("It's true!");
|
||
|
|
} else if bar == baz {
|
||
|
|
print("It's true again!");
|
||
|
|
} else if ... {
|
||
|
|
:
|
||
|
|
} else if ... {
|
||
|
|
:
|
||
|
|
} else {
|
||
|
|
print("It's finally false!");
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
All branches of an `if` statement must be enclosed within braces '`{`' .. '`}`', even when there is only one statement.
|
||
|
|
Like Rust, there is no ambiguity regarding which `if` clause a statement belongs to.
|
||
|
|
|
||
|
|
```rust
|
||
|
|
if (decision) print("I've decided!");
|
||
|
|
// ^ syntax error, expecting '{' in statement block
|
||
|
|
```
|
||
|
|
|
||
|
|
|
||
|
|
`if`-Expressions
|
||
|
|
---------------
|
||
|
|
|
||
|
|
Like Rust, `if` statements can also be used as _expressions_, replacing the `? :` conditional operators
|
||
|
|
in other C-like languages.
|
||
|
|
|
||
|
|
```rust
|
||
|
|
// The following is equivalent to C: int x = 1 + (decision ? 42 : 123) / 2;
|
||
|
|
let x = 1 + if decision { 42 } else { 123 } / 2;
|
||
|
|
x == 22;
|
||
|
|
|
||
|
|
let x = if decision { 42 }; // no else branch defaults to '()'
|
||
|
|
x == ();
|
||
|
|
```
|