golang for loop a string, but it prints 'char' as int, why?

A very simple go function:

func genString(v string) {
	for _, c := range v {
		fmt.Println(c)
	}
}

Called in:

func TestBasics(t *testing.T) {
	genString("abc")
}

Then I ran:

go test -v -run TestBasics xxxxxx

It prints:

97
98
99

I expected that it should print

a
b
c

But it prints the corresponding integer value? Why, how to fix it and print just the char?

Thanks!

> Why

Looping with range over string will give you a sequence of runes.

For range spec:

Range expression                          1st value          2nd value
array or slice  a  [n]E, *[n]E, or []E    index    i  int    a[i]       E
string          s  string type            index    i  int    see below  rune
map             m  map[K]V                key      k  K      m[k]       V
channel         c  chan E, <-chan E       element  e  E

(notice the second row and last column in the table)

> 2. For a string value, the "range" clause iterates over the Unicode code points in the string starting at byte index 0. On successive
> iterations, the index value will be the index of the first byte of
> successive UTF-8-encoded code points in the string, and the second
> value, of type rune, will be the value of the corresponding code
> point. If the iteration encounters an invalid UTF-8 sequence, the
> second value will be 0xFFFD, the Unicode replacement character, and
> the next iteration will advance a single byte in the string.

A rune value is an integer value identifying a Unicode code point.
The type itself is just an alias of int32.

> how to fix it and print just the char

Use fmt.Printf with the %c verb to print the character value, i.e. fmt.Printf("%c\n", c)

fmt printing verbs doc:

Integers:

%b	base 2
%c	the character represented by the corresponding Unicode code point
%d	base 10
%o	base 8
%O	base 8 with 0o prefix
%q	a single-quoted character literal safely escaped with Go syntax.
%x	base 16, with lower-case letters for a-f
%X	base 16, with upper-case letters for A-F
%U	Unicode format: U+1234; same as "U+%04X"

(notice the second row in the table)

for _, c := range "abc" {
	fmt.Printf("%c\n", c)
}

https://go.dev/play/p/BEjJof4XvIk