如何在Dart中打印美元符号$ [英] How do you print a dollar sign $ in Dart

问题描述

我实际上需要在Dart中的变量前面打印一个美元符号。例如：

I need to actually print a Dollar sign in Dart, ahead of a variable. For example:

void main()
{
  int dollars=42;
  print("I have $dollars."); // I have 42.
}

我希望输出为：我有$ 42 。我怎样才能做到这一点？谢谢。

I want the output to be: I have $42. How can I do this? Thanks.

推荐答案

Dart字符串可以是原始字符串，也可以不是原始字符串（正常吗？煮熟了吗？可以解释吗？正式名称）。我将在此处使用解释，因为它描述了您遇到的问题。

Dart strings can be either raw or ... not raw (normal? cooked? interpreted? There isn't a formal name). I'll go with "interpreted" here, because it describes the problem you have.

在原始字符串中， $和 \没有什么特别的含义，他们就像其他角色一样。
在解释的字符串中， $开始插值， \开始转义。

In a raw string, "$" and "\" mean nothing special, they are just characters like any other. In an interpreted string, "$" starts an interpolation and "\" starts an escape.

由于您希望对 $ dollars进行插值，您不能从字面上使用 $，因此您需要对其进行转义：

Since you want the interpolation for "$dollars", you can't use "$" literally, so you need to escape it:

int dollars = 42;
print("I have \$$dollars.");

如果不想使用转义符，可以将原始和解释部分中的字符串组合在一起：

If you don't want to use an escape, you can combine the string from raw and interpreted parts:

int dollars = 42;
print(r"I have $" "$dollars."); 

两个相邻的字符串文字被组合为一个字符串，即使它们是不同类型的字符串。

Two adjacent string literals are combined into one string, even if they are different types of string.

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