String to long float

// StrToFloat.cpp : main project file.

#include "stdafx.h"
#include<iostream>
#include<string.h>
#include<math.h>
using namespace std;

void conversion(long float &convert,char str[])//It is used to convert string into long float(eg--"1.2"=1.2)
{
    int i=0;
    int dot=0,pw=1;
    while(str[i]!='\0')
    {
        if(str[i]=='.')
        {
            convert=convert*1.0;
            dot=1;
            i++;
        }
        else
        {
            if(dot==0)
                convert=convert*10+str[i++]-48;
            else
                convert=convert+pow(1/10.0,pw++)*(str[i++]-48);
        }
    }
}
void validation(char str[],int &id)//2 check the validation and c if it is alphabetic string or float string
{
    for(int i=0;i<strlen(str);i++)
    {
        if(isalpha(str[i]))
        {
            id=1;
            break;
        }
    }
}
int main()
{
    char str[20];
    cout<<"Please enter first string : ";
    cin.getline(str,20,'\n');
    int id=0,i;
    validation(str,id);
    if(id==1)
    {
            cout<<"Sorry, it is not convertible to a long float number.\nPlease enter a valid input..";
            cout<<"\nPress any key to exit..";
            cin.get();
            exit(1);
    }
    else
    {
        cout<<"Congrats!!! You entered a valid input "<<char(1);
        long float convert=0.0;
        conversion(convert,str);
        cout<<"\nAfter converting, the long float number is : "<<convert<<"\n";
        long float convert1=0.0;
        cout<<"\n\nNow, Please enter second string : ";
        cin.getline(str,20,'\n');
        id=0;
        validation(str,id);
        if(id==1)
        {
            cout<<"Sorry, it is not convertible to a long float number.\nPlease enter a valid value..";
            cout<<"\nPress any key to exit..";
            cin.get();
            exit(1);
        }
        else
        {
            long float convert1=0.0;
            cout<<"Congrats!!! You entered a valid input "<<char(1);
            conversion(convert1,str);
            cout<<"\nAfter converting, the long float number is : "<<convert1<<"\n";
            cout<<"\n\nAfter multiplication, the result is : "<<convert*convert1<<"\n\n\n";
        }
    }
    return 0;
}