“ A”和“ A”之间的区别[0]

Question

I write this code for convert TEXT to BINARY

fmt.Printf("%s
", fmt.Sprintf("%08b", "A"))

and not work, print message: %!b(string=0000000A)

but when i changed "A" to "A"[0] work fine:

fmt.Printf("%s
", fmt.Sprintf("%08b", "A"[0]))

output is 01000001

what is difference between above statements?

Answer 1

Golang differentiates strings from bytes.

"A" is a string, technically a read-only slice of bytes. "A"[0] is the first byte in this sequence, whose value is 0x41.

You asked to print first a string ("A"), then secondly a byte ("A"[0]), in a field of eight characters using binary digits. Your first output was funny because you tried to print a string as if it were some kind of byte value. But a sequence of one byte is not the same as a single byte. Your second output was more natural, since you grabbed the first byte of the string (at index 0), obtaining 0x41.