控制流 / 循环
"for"循环
"for-in"循环
"for-in"循环（带索引）
"while"循环
"do-while"循环
"forEach"循环
"loop {}"循环
无限循环
let
mut
sum10 =
0
;
for
i
in
1
.
.11
{
sum10 += i;
}
//sum10 is 55
println!
(
"sum10 is
{sum10}
"
);