我有一个字符串,例如">number1<=number2&&number3>number4||number2=number4",运算符列表为-
var operators = new List<string> {"=", "!", "<", ">", ">=", "<=", "!=","||","&&"};
因此,期望在字符串中的每个运算符前后引入一个空格。
">number1<=number2&&number3>number4||number2=number4">
我尝试了以下代码,但不起作用,例如,<,>=
public static string AddSpaceBeforeAndAfterOperator(string expression) {
var operators = new List<string> {"=", "!", "<", ">", ">=", "<=", "!=", "||", "&&"};
foreach (var op in operators) {
var index = expression.IndexOf(op, StringComparison.Ordinal);
if (index >= 0) {
if (expression.Substring(index - 1) != " ") {
expression = expression.Insert(index-1, " ");
}
expression = expression.Insert(index + op.Length + 1, " ");
}
}
return expression;
}
注意:操作员列表是随机的。
任何帮助都将不胜感激!
我建议使用regex解决方案。
首先,您需要逃离所有操作员,将他们与|
:连接在一起
var operatorsString = string.Join("|",
operators.OrderByDescending(x => x.Length).Select(Regex.Escape).ToArray()
);
// OrderByDescending here because we want the longer operators to be matched first.
接下来,创建regex:
var regex = $"\s*({operatorString})\s*";
使用问题中的operators
数组,数组如下所示:
s*(<=|>=|!=|==||||&&|=|!|<|>)s?*
注意,s*
用于检查运算符是否已被空格包围。如果是,这些空格将被匹配和替换。
替换为:
$1
代码:
Regex.Replace(input, regex, " $1 ");
注意前导空格和尾随空格。
还要注意,Regex
位于System.Text.RegularExpressions
名称空间内。
演示
我不确定这是否是最有效的方法,但使用替换非常简单
public static string AddSpaceBeforeAndAfterOperator(string expression)
{
var operators = new List<string> { "=", "!", "<", ">", ">=", "<=", "!=", "||", "&&" };
foreach (var op in operators)
{
expression = expression.Replace(op, " " + op + " ");
}
return expression;
}