// | + - |
public static bool IsCorrect(string expression)
{
if (expression.Length == 0)
{
return(false);
}
bool isCorrect = false;
bool isCorrectBracket = true;
bool isCorrectSeparators = true;
bool isCorrectOperators = true;
bool haveABracket = false;
for (int i = 0; i < expression.Length; i++)
{
if (expression[i] == '(' || expression[i] == ')')
{
haveABracket = true;
break;
}
}
if (haveABracket)
{
isCorrectBracket = IsCorrectBracket(expression);
}
for (int i = 0; i < expression.Length; i++)
{
if (Contains.ToSeparators(expression[i]) && i == 0)
{
isCorrectSeparators = false;
}
else if (Contains.ToSeparators(expression[i]) &&
!Contains.ToNumbers(expression[i - 1]))
{
isCorrectSeparators = false;
}
if (Contains.ToSeparators(expression[i]) &&
expression.Length - 1 == i)
{
isCorrectSeparators = false;
}
else if (Contains.ToSeparators(expression[i]) &&
!Contains.ToNumbers(expression[i + 1]))
{
isCorrectSeparators = false;
}
if (Contains.ToMathOperators(expression[i]) &&
expression[i] != '-' && i == 0)
{
isCorrectOperators = false;
}
else if (Contains.ToMathOperators(expression[i]) &&
expression[i] != '-' && !Contains.ToNumbers(
expression[i - 1]) && expression[i - 1] != ')')
{
isCorrectOperators = false;
}
if (Contains.ToMathOperators(expression[i]) &&
i == expression.Length - 1)
{
isCorrectOperators = false;
}
else if (Contains.ToMathOperators(expression[i]) &&
expression[i + 1] != '-' && !Contains.ToNumbers(
expression[i + 1]) && expression[i + 1] != '(')
{
isCorrectOperators = false;
}
if (i != 0 && i != expression.Length - 1 &&
Contains.ToMathOperators(expression[i - 1]) &&
Contains.ToMathOperators(expression[i]) &&
Contains.ToMathOperators(expression[i + 1]))
{
isCorrectOperators = false;
}
}
if (isCorrectBracket && isCorrectSeparators && isCorrectOperators)
{
isCorrect = true;
}
return(isCorrect);
}