Conditionals
Ein Großteil der Rust-Syntax wird Ihnen aus C oder C++ bekannt sein:
- Blocks are delimited by curly braces.
- Zeilenkommentare beginnen mit
//
, Blockkommentare werden mit/* ... */
begrenzt - Schlüsselwörter (keywords) wie
if
undwhile
funktionieren gleich. - Variablenzuweisung erfolgt mit
=
, Vergleich erfolgt mit==
.
if
expressions
You use if
expressions exactly like if
statements in other languages:
fn main() { let x = 10; if x < 20 { println!("small"); } else if x < 100 { println!("biggish"); } else { println!("huge"); } }
In addition, you can use if
as an expression. The last expression of each block becomes the value of the if
expression:
fn main() { let x = 10; let size = if x < 20 { "small" } else { "large" }; println!("number size: {}", size); }
This slide should take about 5 minutes.
Because if
is an expression and must have a particular type, both of its branch blocks must have the same type. Show what happens if you add ;
after "small"
in the second example.
When if
is used in an expression, the expression must have a ;
to separate it from the next statement. Remove the ;
before println!
to see the compiler error.