Calculadora Em C++

#include <math.h>

#include <stdio.h>

#include <stdlib.h>

#include <conio.h>

#include <iostream>

#include <fstream>

#include <ctype.h>

#define PI 3.14159265

main ()

{

char opcao;

float valor1,valor2,result;

printf("\n\t\xC9\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xBB");

printf("\n\t\xBA\t C A L C U L A D O R A \t\xBA");

printf("\n\t\xC8\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xCD\xBC\n");

printf("\n\n\n\t(+)SOMA\n\t(*)MULTIPLICACAO\n\t(-)SUBTRACAO\n\t(/)DIVISAO\n\t(E)EXPONENCIACAO\n\t(R)RAIZ QUADRADA\n\t(P)PORCENTAGEM\n\t(S)SAIR\n\n\tOPCAO: ");

opcao = getche();

//opcao = toupper (opcao);

//printf("%s teste");

switch(opcao){

case '+' :printf("\n\n\t S O M A\n");

printf("\n\t Digite o primeiro valor: ");

scanf("%f",&valor1);

printf("\n\t Digite o segundo valor: ");

scanf("%f",&valor2);

result= valor1+valor2;

printf("\n\n\t O VALOR DA SOMA %c: %.2f\n\n",130,result);break;

case '*':printf("\n\n\t M U L T I P L I C A C A O\n");

printf("\n\t Digite o primeiro valor: ");

scanf("%f",&valor1);

printf("\n\t Digite o segundo valor: ");

scanf("%f",&valor2);

result= valor1*valor2;

printf("\n\n\t O VALOR DA MULTIPLICACAO %c: %.2f\n\n",130,result);break;

case '-':printf("\n\n\t S U B T R A C A O\n");

printf("\n\t Digite o primeiro valor: ");

scanf("%f",&valor1);

printf("\n\t Digite o segundo valor: ");

scanf("%f",&valor2);

result= valor1-valor2;

printf("\n\n\t O VALOR DA SUBTRACAO %c: %.2f\n\n",130,result);break;

case '/':printf("\n\n\t D I V I S A O\n");

printf("\n\t Digite o primeiro valor: ");

scanf("%f",&valor1);

printf("\n\t Digite o segundo valor: ");

scanf("%f",&valor2);

result= valor1/valor2;

if(valor2==0){

printf("\n\t ERRO DIVISAO POR ZERO\n\n");