Code

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Highlighting

A code fence is highlighted for its language (c, bash, asciidoc, js, and the rest highlight.js knows); a fence in a language it doesn’t know, or none, is left plain.

Picking out lines

Braces after the language pick out lines, counted from 1 inside the fence: {3,5-7} makes them stand out and the rest fade, and {numbers} numbers every line. Ranges separated by | take turns: on a slide, the first stands out when the fence appears, and each n moves on to the next.

```c {numbers 2|4-5}
#include <stdio.h>
int main(void) {
  printf("hi\n");
  return 0;
}
```

#include <stdio.h>
int main(void) {
  printf("hi\n");
  return 0;
}

Callouts

A line can carry a note, as AsciiDoc’s callouts do: <1> at the end of the line, after a space or in a comment of its own (// <1>), and the note right after the fence. The marker becomes a numbered badge, and the notes a list under the code; hovering a note marks its line, and the other way round.

```java
numbers.stream()
  .gather(Gatherers.scan(() -> 0, Integer::sum)) <1>
  .forEach(System.out::println); // <2>
```
<1> `scan()` emits the running sum so far
<2> one line per running sum

numbers.stream()
  .gather(Gatherers.scan(() -> 0, Integer::sum))
  .forEach(System.out::println);

On a slide, the code appears with none of its lines picked out, and each n moves to the next callout, showing its note. Braces that pick out lines take over the steps, and each note shows when its line first stands out.

Output

What the code prints goes in an output fence right after it. It’s drawn attached under the code, tinted and bold, and a callout can mark its lines too, with the notes after both fences.

```java
numbers.stream().gather(Gatherers.scan(() -> 0, Integer::sum)).forEach(System.out::println);
```
```output
1
3
6
```

numbers.stream().gather(Gatherers.scan(() -> 0, Integer::sum)).forEach(System.out::println);

1
3
6

On a slide, the output appears with the first callout in it, or as a step of its own after the code’s. Output longer than 12 lines is cut short, with a link to show all of it; on a slide or on paper, it’s whole.

More than one language

The same code in more than one language goes in a tabs block; see Layout.