What is the difference between iterating over a string using `for range` and a rune slice, and why does this difference occur?

Ranging over Strings and Rune Slices: Differences and Similarities

Question

When iterating over a string using for range and a rune slice ([]rune(str)), one might expect similar results. However, there exists a subtle difference between the two approaches. Can you identify it and explain why it occurs?

Answer

While both for range loops over strings and rune slices yield the same result for basic characters (e.g., ASCII), a difference arises when dealing with multibyte characters.

String Indexing

Strings are essentially sequences of bytes. Indexing a string is appropriate for manipulating bytes or when dealing with single-byte characters. However, indexing can be problematic when working with multibyte characters.

Range Loops on Strings

The for range loop over strings behaves uniquely. It combines the characteristics of both byte and rune slices.

• The index i indicates the byte position of the start of the current code point.
• The variable c represents a rune, potentially consisting of multiple bytes.

This special behavior of for range loops over strings means that the index i can increment by more than one during iterations, especially when the string contains multibyte characters.

Conclusion

When working with multibyte characters, the choice between ranging over the string or its rune slice depends on the desired behavior. For manipulating bytes, indexing a string is suitable. For working with characters or code points, using []rune(str) and ranging over it provides clearer and more intuitive results.

The above is the detailed content of What is the difference between iterating over a string using `for range` and a rune slice, and why does this difference occur?. For more information, please follow other related articles on the PHP Chinese website!