二元运算符“+”不能应用于“_”和“String”类型的操作数

Question

I am new to swift.我是 swift 的新手。 I want to use the function reduce to concatenate names in an array my code:我想使用函数 reduce 将我的代码数组中的名称连接起来：

let names = ["ZZZZZZ", "B", "AA", "CCCC", "EEEEE"]
let sum = names.reduce(0) {
return $0 + $1
}

and I get this error Binary operator '+' cannot be applied to operands of type '_' and 'String'并且我收到此错误二进制运算符“+”不能应用于“_”和“字符串”类型的操作数

Answer 1

If you want to reduce strings the default value must be an empty string ""如果要reduce字符串，默认值必须是空字符串""

let sum = names.reduce("") { return $0 + $1 }

Actually实际上

let sum = names.joined()

does the same.做同样的事情。