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Conversions to and from a string type

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3. Converting a value of a string type to a slice of bytes type yields a non-nil slice whose successive elements are the bytes of the string.

[]byte("hellø")             // []byte{'h', 'e', 'l', 'l', '\xc3', '\xb8'}
[]byte("")                  // []byte{}

bytes("hellø")              // []byte{'h', 'e', 'l', 'l', '\xc3', '\xb8'}

[]myByte("world!")          // []myByte{'w', 'o', 'r', 'l', 'd', '!'}
[]myByte(myString("🌏"))    // []myByte{'\xf0', '\x9f', '\x8c', '\x8f'}

4. Converting a value of a string type to a slice of runes type yields a slice containing the individual Unicode code points of the string.

[]rune(myString("白鵬翔"))   // []rune{0x767d, 0x9d6c, 0x7fd4}
[]rune("")                  // []rune{}

runes("白鵬翔")              // []rune{0x767d, 0x9d6c, 0x7fd4}

[]myRune("♫♬")              // []myRune{0x266b, 0x266c}
[]myRune(myString("🌐"))    // []myRune{0x1f310}

There should be no surprises here, as these are just the inverse of the previous two rules. The only exception here is that while you can convert from a nil byte slice or rune slice to a empty string, there is no way to convert from a string to an nil byte or rune slice.

Tomorrow we’ll over the last rule regarding string conversions.

Quotes from The Go Programming Language Specification Language version go1.22 (Feb 6, 2024)