Odin by Example: Strings

Strings hold UTF-8 encoded text. A string stores a pointer to data and a byte length, it does not own the underlying memory.

The built-in len procedure returns the number of bytes in a string, not the number of characters.

Indexing a string yields a byte (u8), not a rune. Use a for loop to iterate over runes, or index manually to access individual bytes.

Constant strings can be concatenated with + at compile time. Use strings.concatenate for runtime concatenation. Strings can be compared with == and !=.

$ odin run strings.odin -file
Hellope!
len: 8
first byte: 72
Hellope!
Hellope!, world!
equal: true
0 H
1 e
2 l
3 l
4 o
5 p
6 e
7 !
bytes: 5
0 99
1 97
2 102
3 195
4 169

package main

import "core:fmt"
import "core:strings"

main :: proc() {
	// Create a string from a literal.
	s := "Hellope!"
	fmt.println(s)

	// len returns the number of bytes.
	fmt.println("len:", len(s))

	// Indexing returns a byte (u8).
	fmt.println("first byte:", s[0])

	// + concatenates constant strings at compile time.
	fmt.println("Hello" + "pe!")

	// For variables, use strings.concatenate.
	greeting := strings.concatenate({s, ", world!"})
	fmt.println(greeting)

	// Compare strings with == and !=.
	fmt.println("equal:", s == "Hellope!")

	// Iterate over runes. Odin decodes UTF-8
	// automatically.
	for r, i in s {
		fmt.println(i, r)
	}

	// UTF-8: len counts bytes, not characters.
	word := "café"
	fmt.println("bytes:", len(word))

	// Indexing gives raw bytes. The é character
	// uses two bytes in UTF-8.
	for i in 0..<len(word) {
		fmt.println(i, word[i])
	}
}

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