使用 & 进行字符串操作或 + 在 VB.NET 中 [英] String manipulation with & or + in VB.NET

问题描述

我见过几个程序员使用 & 和 + 进行字符串操作.

I have seen several programmers use & and + for string manipulation.

如:

dim firstvar as string
dim secondvar as string
dim thirdvar as string

thirdvar = firstvar & secondvar

或者是:

thirdvar = firstvar + secondvar

有关系吗?如果是，为什么?

Does it matter? If so, why?

推荐答案

<代码>+ 和 & 运算符在 VB.NET 中不相同.

使用 & 运算符表示您打算连接字符串，而 + 运算符表示您打算添加数字.使用 & 运算符会将操作的两边都转换为字符串.当您有混合类型(表达式的一侧是字符串，另一侧是数字)时，您对运算符的使用将决定结果.

Using the & operator indicates your intention to concatenate strings, while the + operator indicates your intention to add numbers. Using the & operator will convert both sides of the operation into strings. When you have mixed types (one side of the expression is a string, the other is a number), your usage of the operator will determine the result.

1 + "2" = 3 'This will cause a compiler error if Option Strict is on'
1 & "2" = "12"
1 & 2 = "12"
"text" + 2 'Throws an InvalidCastException since "text" cannot be converted to a Double'

所以，我的指导方针(除了避免像那样混合类型)是在连接字符串时使用 & ，只是为了确保编译器清楚您的意图，并避免不可能- 查找涉及使用 + 运算符进行连接的错误.

So, my guideline (aside from avoiding mixing types like that) is to use the & when concatenating strings, just to make sure your intentions are clear to the compiler, and avoid impossible-to-find bugs involving using the + operator to concatenate.

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