使用“.ToString()”带有数字变量

发布于 2024-11-13 07:32:23 字数 190 浏览 1 评论 0原文

将数值转换为 string 时省略 .ToString() 有什么缺点吗？

int i = 1234;
string s;
// Instead of
s = "i is " + i.ToString();
// Writing
s = "i is " + i;

原文

Is there any drawback for omitting .ToString() while converting numeric values to string ?

int i = 1234;
string s;
// Instead of
s = "i is " + i.ToString();
// Writing
s = "i is " + i;

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月下伊人醉 2024-11-20 07:32:23

在这种情况下没有什么区别。

"Count: " + i

编译为

String.Concat("Count: ",i)

String.Concat 具有多个重载，并且我相信选择了 Concat(Object, Object) 重载（因为 string 和 int 的唯一共同祖先是 object）。

内部实现是这样的：

 return (arg0.ToString() + arg1.ToString());

如果您调用

"Count: " + i.ToString()

，那么它会选择 Concat(String, String) 重载，因为两者都是字符串。

因此，对于所有实际问题，它本质上都是做同样的事情 - 它隐式调用 i.ToString()。

在上述情况下，我通常会省略 .ToString，因为它只会增加噪音。

It doesn't make a difference in this case.

"Count: " + i

compiles down to

String.Concat("Count: ",i)

String.Concat has multiple overloads, and I believe that the Concat(Object, Object) overload is chosen (since the only common ancestor of string and int is object).

The internal implementation is this:

 return (arg0.ToString() + arg1.ToString());

If you call

"Count: " + i.ToString()

then it chooses the Concat(String, String) overload since both are strings.

So for all practical matters, it's essentially doing the same anyway - it's implicitly calling i.ToString().

I usually omit .ToString in cases like the above because it just adds noise.

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无畏 2024-11-20 07:32:23

尽管事实上它无法编译（至少如果不在第一个 i 前面添加另一个 "" 就不会使用 Visual Studio 2008），但还是存在差异，具体取决于关于如何使用它（假设它可以工作）以及处理运算符的顺序（在 C# 中，我猜几乎所有语言 + 的优先级都高于 =）：

int i = 1234;
string s;
s = i.ToString(); // "1234"
s = i.ToString() + i.ToString(); // "12341234"
s = i; // "1234"
s = i + i; // "2468" (but only if you don't add "" in front)

编辑：
使用更新后的代码，假设您不使用括号对多个非字符串对象/变量进行分组，则没有真正的区别：

int i = 1234;
string s;
s = "" + i + i; // "12341234"
s = "" + (i + i); // "2468"

Despite the fact it won't compile (at least it won't using Visual Studio 2008 without adding another "" in front of the first i) there ARE differences, depending on how you use it (assuming it would work) and in which order operators are handled (in C# and I guess almost all languages + has a higher priority than =):

int i = 1234;
string s;
s = i.ToString(); // "1234"
s = i.ToString() + i.ToString(); // "12341234"
s = i; // "1234"
s = i + i; // "2468" (but only if you don't add "" in front)

Edit:
With the updated code there's no real difference assuming you don't use brackets to group several non-string objects/variables:

int i = 1234;
string s;
s = "" + i + i; // "12341234"
s = "" + (i + i); // "2468"

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冬天旳寂寞 2024-11-20 07:32:23

我能想到的唯一缺点是您可以将其他参数添加到 ToString() 中。

但在大多数情况下，您可以将字符串与 int 连接起来，我认为更好的解决方案是使用 string.Format() ：

string.Format("i is {0}", i);

在您的情况下，这种方式更好并不那么明显，但是您开始考虑添加适当的标点符号（i is {0}.），以其他方式稍微改变输出，或者支持本地化，这种方式的优点变得显而易见。

The only drawback I can think of is that you can put additional parameters to ToString().

But in most cases where you could concatenate string with an int, I think the better solution is to use string.Format():

string.Format("i is {0}", i);

In your case, it's not as obvious that this way is better, but you start thinking about adding proper punctuation (i is {0}.), changing the output slightly in some other way, or supporting localization, the advantages of this way become clear.

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