Cod sursa(job #790255)

Utilizator ArmandNMArmand Nicolicioiu ArmandNM Data 20 septembrie 2012 18:42:11
Problema Evaluarea unei expresii Scor 40
Compilator cpp Status done
Runda Arhiva educationala Marime 0.88 kb
#include <fstream>
using namespace std;
ifstream f("evaluare.in");
ofstream g("evaluare.out");
int l,i;
char s[100001];

float eval();
float termen();
float factor();

float eval()
{
	float r=termen();
	while (s[i]=='+' || s[i]=='-')
	{
		if (s[i]=='+')
		{
			i++;
			r=r+termen();
		}
		if (s[i]=='-')
		{
			i++;
			r=r-termen();
		}
	}
	return r;
}

float termen()
{
	float r=factor();
	while (s[i]=='*' || s[i]=='/')
	{
		if (s[i]=='*')
		{
			i++;
			r *= factor();
		}
		if (s[i]=='/')
		{
			i++;
			r /= factor();
		}
	}
	return r;
}

float factor()
{
	float r=0;
	if (s[i]=='(') { i++; //Trec peste '('
					r=eval(); 
					i++; // Trec peste ')'
	}
	else
	while (s[i]>='0' && s[i]<='9')
	{
		r=r*10+float(s[i]-'0');
		i++;
	}
	return r;
}

int main()
{
	f.getline(s,1000);
	g<<eval();
	f.close(); g.close();
	return 0;
}