ruby 数组类型错误：无法将 Fixnum 转换为字符串
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Array TypeError: can't convert Fixnum into String
提问by Billjk
I am experimenting with arrays, and am reading the book "Beginning Ruby on Rails" by Steve Holzner. I made the program:
我正在试验数组，并且正在阅读 Steve Holzner 所著的“Beginning Ruby on Rails”一书。我做了这个程序：
array = ['Hello', 'there', 1, 2]
puts array[1]
puts array[3]
puts array.length
array2 = Array.new
puts array2.length
array2[0] = "Banana"
array2[1] = 6
puts array2[0] + " " + array2[1]
puts array3.length
It doesn't do much, but when i run it i get the error
它没有做太多，但是当我运行它时，我收到错误
arrays.rb:9:in `+': can't convert Fixnum into String (TypeError)
from arrays.rb:9
Why do I get this error?
为什么我会收到这个错误？
回答by JP Silvashy
You can't add a string and a integer (Fixnum), in this case you tried to add 6 to "Banana".
您不能添加字符串和整数 ( Fixnum)，在这种情况下，您尝试将 6 添加到“香蕉”。
If on line 9 you did this:
如果在第 9 行你这样做了：
puts array2[0] + " " + array2[1].to_s
You would get:
你会得到：
"Banana 6"
回答by Marc Talbot
array2[1]is 6, which is a Fixnum. It doesn't know how to add itself to a string (which in this case is Banana. If you were to convert it to a string, it would work just fine.
array2[1]is 6，这是一个 Fixnum。它不知道如何将自己添加到一个字符串中（在这种情况下是Banana. 如果您要将其转换为字符串，它会工作得很好。
puts array2[0] + " " + array2[1].to_s
回答by Kevin Jalbert
The error is basically saying you cannot convert array2[1](the value is a number, a type Fixnumin this case) into a Stringtype. The way you would work around this is to convert the type into a String(this is for line 9 where the error occurs):
该错误基本上是说您无法将array2[1]（值是一个数字，在本例中为Fixnum类型）转换为String类型。解决此问题的方法是将类型转换为字符串（这是针对发生错误的第 9 行）：
puts array2[0] + " " + array2[1].to_s
The array2[1].to_sconverts the number into a String type.
数组2[1]。to_s将数字转换为 String 类型。
回答by Chetter Hummin
Haven't tried this myself, but try replacing
自己没试过，但尝试更换
puts array2[0] + " " + array2[1]
with
和
puts array2[0] + " " + array2[1].to_s
回答by Aaron
Here is a way to convert a FixNum expression into a string,
这是一种将 FixNum 表达式转换为字符串的方法，
x=2
print (x+20).to_s + "\sbanannas"
Didn't know you could tack on the FixnNum#to_s method to those parens.
不知道您可以将 FixnNum#to_s 方法添加到这些括号中。
回答by Yoseph.B
you are trying to add an integer(fixnum) and a string, which is something you can't do on ruby unless you explicitly cast the integer(fixnum) to a string. in your code array2[0]holds a string value "banannas" and array2[1]holds an integer(fixnum) value 1. so for your code too run correctly you need too cast the value in array2[1] to a string value.
您正在尝试添加一个 integer(fixnum) 和一个字符串，除非您明确将 integer(fixnum) 转换为字符串，否则您无法在 ruby 上执行此操作。在您的代码中array2[0]保存一个字符串值“banannas”并array2[1]保存一个整数（fixnum）值 1。所以为了您的代码也能正确运行，您也需要将 array2[1] 中的值转换为字符串值。
you can change your code on line 9 to this:
您可以将第 9 行的代码更改为：
puts array2[0] + " " + array2[1]._s
