c# - LastIndexOfAny not working

Question

I have this line in my C# code:

s_ind = formula.LastIndexOfAny(operators, 1);

Where operators is a char array with elements, +, -, *, /, and ^

formula is a string equal to "182+0"

The expression is returning -1, so it is saying there is no plus sign in the string "182+0"

What is going wrong?

Answer 1

1告诉从LastIndexOfAny位置 1 开始并向后搜索。由于您+在位置 1之后，因此找不到它。

如果你想找到最后一次出现，只需使用：

s_ind = formula.LastIndexOfAny(operators);

来自MSDN：

搜索从指定的字符位置开始，然后向后向字符串的开头进行