Help needed with first c++ program: a simple calculator

Iv only been learning c++ for two days, so please forgive any noobish errors.

The problem im having is that i cant get the program to deal with numbers longer than 7 characters in lenth without it printing in standard form (it prints 1,000,000 as 1e+06). At first i thought i just needed to use "double" instead of "float", but this hasn't help. I'v changed it now to "long double" and it hasn't helped either.

Code:

` #include <stdio.h>`

#include <iostream>

using namespace std;

long double calc(long double num,long double num1,char function, long double neq, char mult, char div, char add, char sub, int cal);

int fin(long double neq, int cal);

int main(int argc, char *argv[]){

int x;

while (x==x){

long double num;

long double num1;

long double neq;

char function;

char mult;

char div;

char add;

char sub;

int cal;

mult='*';

div='/';

add='+';

sub='-';

cout<<"Please enter your calculation, seperated by spaces, and press enter:" <<"\n";

cin>>num >>function >>num1;

cin.ignore();

calc(num, num1, function, neq, mult, div, add, sub, cal);}}

long double calc(long double num,long double num1,char function, long double neq, char mult, char div, char add, char sub, int cal){

if(function==mult){

neq=num * num1;

cal=1;}

else if(function==div){

neq=num / num1;

cal=1;}

else if(function==add){

neq=num + num1;

cal=1;}

else if(function==sub){

neq=num - num1;

cal=1;}

else{

cal=0;}

fin(neq, cal);}

int fin(long double neq,int cal){

if(cal==1){

cout<<"\n" <<neq <<"\n";}

else if(cal==0){

cout<<"Operation error, please re-enter your calculation" <<"\n\n";

return 0;}}

Im sorry there are no comments, i realy need to get into the habbit of using them. Many thanks in advance.