bool parantezareValida()
{
	int top = -1, i = 0;
	char stiva[NMAX];
	while (i<lungimeSirInit && top >-2)
	{
		if (sir[i] == '(')
			if (sir[i + 1] == ')')
				return 0;
			else
			{
				top++;
				stiva[top] = '(';
			}
		else if ((sir[i] == ')'))
		{
			top--;
		}
		i++;
	}
	if (top != -1)
		return 0;
	return 1;
}


int nrDinString(char s[])
{
	/// presupunem ca s e numar
	int nr = 0, p = 1, i;
	for (i = strlen(s) - 1; i >= 0; i--)
	{
		nr += (p * (s[i] - 48));
		p *= 10;
	}
	return nr;
}

bool esteFunctie(char s[])
{
    for(int j = 0 ; j < 7 ; j++)
        if(strcmp(s,functii[j])==0)
            return 1;
	return 0;
}

bool sirValid(char s[])
{
	int i = 0, nrCifre = 0, nrCaractere = 0;
	char aux[NRCHAR];
	if (!parantezareValida())
	{
		cout << "parantezare gresita";
		return 0;
	}
	while (i < lungimeSirInit)
	{
		///if(!((s[i]>='a'&&s[i]<='z')||(s[i]>='0'&&s[i]<='9')||(strchr(operatori, s[i])!=NULL)||(s[i]==')')||s[i]=='('))
		if (s[i] == ')' || s[i] == '(' || strchr(operatori, s[i]))
		{
			if (nrCaractere >= NRCHAR)
			{
				cout << "prea multe litere";
				return 0;
			}
			if (nrCifre >= NRCHAR)
			{
				cout << "numar prea mare";
				return 0;
			}
			nrCaractere = nrCifre = 0;
		}
		else if (s[i] >= '0' && s[i] <= '9')
		{
			nrCifre++;
			if (s[i + 1] >= 'a' && s[i + 1] <= 'z')
			{
				cout << "expresie incorecta";///exemplu: 2x
				return 0;
			}
			if (nrCaractere >= NRCHAR)
			{
				cout << "prea multe litere";
				return 0;
			}
			nrCaractere = 0;
		}
		else if (s[i] >= 'a' && s[i] <= 'z')
		{
			if (nrCifre >= NRCHAR)///numar prea mare de cifre
			{
				cout << "numar prea mare";
				return 0;
			}
			nrCifre = 0;
			aux[nrCaractere] = s[i];
			nrCaractere++;
			if (!((s[i + 1] >= 'a' && s[i + 1] <= 'z') || (s[i + 1] >= 'A' && s[i + 1] <= 'Z')))
			{
				aux[nrCaractere] = '\0';
				if (!esteFunctie(aux) && strcmp(aux, "x") != 0 && strcmp(aux, "e") != 0 && strcmp(aux, "pi") != 0)
				{
					cout << "functie nerecunoscuta:" << aux;
					return 0;
				}
			}
		}
		else
		{
			cout << "caracter nepermis:" << s[i];
			return 0;
		}
		i++;
	}
	return 1;
}