Possible Loss of data

Hi everyone, I've posted codes for C++ in the past but am now trying to learn c. I successfully converted the following program into C from c++. It was a pretty easy conversion, the only problem I had were with the warnings. I could not figure out (using only the book) why I kept receiving the warnings. The message runs successfully but I just wanted to understand the program a little bit better and see how I could change it to remove those warnings. All 8 warnings state

warning C4244: '=' : conversion from 'double ' to 'float ', possible loss of data

If you can steer me in the right direction I would greatly appreciate it..especially since I'm used to programming in C++ and C although is basically the same, confuses me every once in a while.

Thanks

Code:

---


    //

//This program will assist
//in calculating the costs of 4 major vacation packages


#include<iostream.h>
#include <stdio.h>


//The data structures

struct Package1                                  //Climbing package
{
        int Num;                                          //Number in party
        int Beginners;                                  //Those needing instructions
        int Advanced;                                  //Those not needing instructions
        int NeedEquip;                                  //Those renting camping equipments
        float BaseCharges;                      //Base charges
        float Charges;                                  //Total charges
        float Instruction;                      //Cost of instruction
        float Equipment;                          //Cost of equipment rental
        float Discount;                              //Discount
        float Deposit;                                  //Required deposit
};

struct Package2                                  //Scuba package
{
        int Num;                                          //Number in party
        int Beginners;                                  //Those needing instructions
        int Advanced;                                  //Those not needing instructions
        float BaseCharges;                      //Base charges
        float Charges;                                  //Total charges
        float Instruction;                      //Cost of instruction
        float Discount;                              //Discount
        float Deposit;                                  //Required deposit
};

struct Package3                                  //Sky Diving Package
{
        int Num;                                          //Number in party
        int Lodge1;                                          //Number at 1st lodging choice
        int Lodge2;                                          //Number at 2nd lodging choice
        float BaseCharges;                      //Base charges
        float Charges;                                  //Total charges
        float Discount;                              //Discount
        float Lodging;                                  //Cost of lodging
        float Deposit;                                  //Required deposit
};

struct Package4                                  //Spelunking Package
{
        int Num;                                          //Number in party
        int NeedEquip;                                  //Those renting camping equipments
        float BaseCharges;                      //Base charges
        float Charges;                                  //Total charges
        float Equipment;                          //Cost of equipment rental
        float Discount;                              //Discount
        float Deposit;                                  //Required deposit
};

union Pack                                                  //Combines all four structs
{
  struct Package1 Climb;
  struct Package2 Scuba;
  struct Package3 Sky;
  struct Package4 Spel;
};

struct Reservation
{
        int PackNum;                                  //Indicates which package is stored
    union Pack Packs;
};

//Constants for the charges
const float ClimbRate = 350.0;                        //Base rate - Devil's Courthouse
const float ScubaRate = 1000.0;                        //Base Rate - Bahamas
const float SkyDiveRate = 400.0;                //Base Rate - Sky diving
const float CaveRate = 700.0;                        //Base Rate - Spelunking
const float ClimbInstruct = 100.0;                //Climbing instructions
const float ScubaInstruct = 100.0;                //Scuba instructions
const float DailyCampRental = 40.0;                //Daily camping equip. rental
const float DayLodge1 = 65.0;                        //Lodging option (sky diving)
const float DayLodge2 = 120.0;                        //Lodging option (sky diving)

//Function prototypes
void Climbing(struct Reservation*);
void Scuba(struct Reservation*);
void SkyDive(struct Reservation*);
void Spelunk(struct Reservation*);
int Menu(void);
void DisplayInfo(const struct Reservation*);
void DisplayPack1(const struct Reservation*);
void DisplayPack2(const struct Reservation*);
void DisplayPack3(const struct Reservation*);
void DisplayPack4(const struct Reservation*);


//Main function
main()
{
        int Selection;
        struct Reservation Group;
 do
        {
                Selection = Menu();
                switch (Selection)
                {
                case 1: Climbing(& Group);
                                break;
                case 2: Scuba(& Group);
                                break;
                case 3: SkyDive(& Group);
                                break;
                case 4: Spelunk(& Group);
                                break;
      case 5: printf("Exiting program.\n\n");  //(cout had been changed to printf for c conversion)
                }

                if (Selection <5)
        DisplayInfo(& Group);
        } while (Selection != 5);

        return 0;
}

//Definition of function Menu.
//Displays the main menu and asks the user to select an option.
//Returns an integer in the range 1 - 5.

int Menu(void)
{
        int Choice;
        do
        {
      printf("\nHigh Adventure Travel Agency\n");
      printf("------------------------------\n");
      printf("1) Devil's Courthouse Adventure Weekend\n");
      printf("2) Scuba Bahama\n");
      printf("3) Sky Dive Colorado\n");
      printf("4) Barron Cliff Spelunk\n");
      printf("5) Exit program\n\n");
      printf("Enter 1, 2, 3, 4, or 5: ");
                scanf("%d", &Choice);                  //(cin has been changed to scanf for c conversion)

                if (Choice < 1 || Choice > 5)          //If choice is less than 1 or greater than 5
      printf("Invalid Selection\n");            //Cout/printf "Invalid Selection

        } while (Choice < 1 || Choice > 5);          //?????????????

        return Choice;
}

//Definition of Climbing function.
// Uses a Reservation reference parameter to hold the vacation
// package information. This function calculates the charges for
// the Devil's Courthouse Adventure Weekend package. 

void Climbing(struct Reservation *Group)
{
  (*Group).PackNum = 1;

  printf("\nDevil's Courthouse Adventure Weekend\n");
        printf("--------------------------------------\n");
        printf("How many will be going who need an instructor? ");
        scanf("%d", &(*Group).Packs.Climb.Beginners);
        printf("How many advanced climbers will be going? ");
        scanf("%d", &(*Group).Packs.Climb.Advanced);

  (*Group).Packs.Climb.Num =(*Group).Packs.Climb.Beginners + (*Group).Packs.Climb.Advanced;

        printf("How many will be rent camping equipment? ");
  scanf("%d", &(*Group).Packs.Climb.NeedEquip);

        //Calculate base charges
        (*Group).Packs.Climb.BaseCharges = (*Group).Packs.Climb.Num * ClimbRate;
        (*Group).Packs.Climb.Charges = (*Group).Packs.Climb.BaseCharges;

        //Calculate 10% discount for 5 or more
        if ((*Group).Packs.Climb.Num > 4)
        {
                (*Group).Packs.Climb.Discount = (*Group).Packs.Climb.Charges * .10;
                (*Group).Packs.Climb.Charges -= (*Group).Packs.Climb.Discount;
        }
        else
                (*Group).Packs.Climb.Discount = 0;

        //Add cost of instruction
        (*Group).Packs.Climb.Instruction = (*Group).Packs.Climb.Beginners * ClimbInstruct;
        (*Group).Packs.Climb.Charges += (*Group).Packs.Climb.Instruction;

        //Add cost of camping equipment rental
        (*Group).Packs.Climb.Equipment = (*Group).Packs.Climb.NeedEquip * DailyCampRental * 4;
        (*Group).Packs.Climb.Charges += (*Group).Packs.Climb.Equipment;

        //Calculate required deposit
        (*Group).Packs.Climb.Deposit = (*Group).Packs.Climb.Charges / 2.0;
}

//Definition of Scuba function.
//Uses a Reservation reference parameter to hold
//the vacation package information.
//This function calculates the charges for the Scuba Bahama package.

void Scuba(struct Reservation *Group)
{
        (*Group).PackNum = 2;

  printf("\nScuba Bahama\n");
        printf("--------------\n");
        printf("How many will be going who need an instructor? ");
        scanf("%d", &(*Group).Packs.Scuba.Beginners);
        printf("How many advanced scuba divers will be going? ");
        scanf("%d", &(*Group).Packs.Scuba.Advanced);

        (*Group).Packs.Scuba.Num = (*Group).Packs.Scuba.Beginners + (*Group).Packs.Scuba.Advanced;

        //Calculate base charges
        (*Group).Packs.Scuba.BaseCharges = (*Group).Packs.Scuba.Num * ScubaRate;
        (*Group).Packs.Scuba.Charges = (*Group).Packs.Scuba.BaseCharges;

        //Calculate 10% discount for 5 or more
        if ((*Group).Packs.Scuba.Num > 4)
        {
                (*Group).Packs.Scuba.Discount = (*Group).Packs.Scuba.Charges * .10;
                (*Group).Packs.Scuba.Charges -= (*Group).Packs.Scuba.Discount;
        }
        else
                (*Group).Packs.Scuba.Discount = 0;

        //Add cost of instruction
        (*Group).Packs.Scuba.Instruction = (*Group).Packs.Scuba.Beginners * ScubaInstruct;
        (*Group).Packs.Scuba.Charges += (*Group).Packs.Scuba.Instruction;

        //Calculate required deposit
        (*Group).Packs.Scuba.Deposit = (*Group).Packs.Scuba.Charges / 2.0;
}

//Definition of Sky Dive function.
//Uses a Reservation reference parameter to hold
//the vacation package information.
//This function calculates the charges for the Sky Dive Colorado package. */

void SkyDive(struct Reservation *Group)
{
        (*Group).PackNum = 3;

  printf("\nSky Dive Colorado\n");
        printf("-------------------\n");
        printf("How many will be going? ");
        scanf("%d", &(*Group).Packs.Sky.Num);

        //Calculate base charges
        (*Group).Packs.Sky.BaseCharges = (*Group).Packs.Sky.Num * SkyDiveRate;
        (*Group).Packs.Sky.Charges = (*Group).Packs.Sky.BaseCharges;

        //Calculate 10% discount for 5 or more
        if ((*Group).Packs.Sky.Num > 4)
        {
                (*Group).Packs.Sky.Discount = (*Group).Packs.Sky.Charges * .10;
                (*Group).Packs.Sky.Charges -= (*Group).Packs.Sky.Discount;
        }
        else
                (*Group).Packs.Sky.Discount = 0;

        //Calculate lodging costs
  printf("How many will stay at Wilderness Lodge? ");
        scanf("%d", &(*Group).Packs.Sky.Lodge1);
        printf("How many will stay at Luxury Inn? ");
        scanf("%d", &(*Group).Packs.Sky.Lodge2);

  (*Group).Packs.Sky.Lodging = ((*Group).Packs.Sky.Lodge1 * DayLodge1) + ((*Group).Packs.Sky.Lodge2 * DayLodge2);

        //Calculate required deposit
        (*Group).Packs.Sky.Deposit = (*Group).Packs.Sky.Charges / 2.0;
}

//Definition of Spelunk function.
//Uses a Reservation reference parameter to hold
//the vacation package information.
//This function calculates the charges for the Barron Cliff Spelunk package.

void Spelunk(struct Reservation *Group)
{
        (*Group).PackNum = 4;

  printf("\nBarron Cliff Spelunk Weekend\n");
        printf("----------------------\n");
        printf("How many will be going? ");
        scanf("%d", &(*Group).Packs.Spel.Num);
        printf("How many will rent camping equipment? ");
        scanf("%d", &(*Group).Packs.Spel.NeedEquip);

        //Calculate base charges
        (*Group).Packs.Spel.BaseCharges = (*Group).Packs.Spel.Num * CaveRate;
        (*Group).Packs.Spel.Charges = (*Group).Packs.Spel.BaseCharges;

        //Calculate 10% discount for 5 or more */
        if ((*Group).Packs.Spel.Num > 4)
        {
                (*Group).Packs.Spel.Discount = (*Group).Packs.Spel.Charges * .10;
                (*Group).Packs.Spel.Charges -= (*Group).Packs.Spel.Discount;
        }
        else
                (*Group).Packs.Spel.Discount = 0;

        //Add cost of camping equipment rental */
        (*Group).Packs.Spel.Equipment = (*Group).Packs.Spel.NeedEquip * DailyCampRental * 4;
        (*Group).Packs.Spel.Charges += (*Group).Packs.Spel.Equipment;

        //Calculate required deposit
        (*Group).Packs.Spel.Deposit = (*Group).Packs.Spel.Charges / 2.0;
}

//Definition of function DisplayInfo.
//Uses a constant Reservation reference parameter to hold the vacation package information.
//This function looks in the Group.Packnum member to determine which
//function to call to display the vacation package information.

void DisplayInfo(const struct  Reservation *Group)
{
        switch ((*Group).PackNum)
        {
                case 1: DisplayPack1(& (*Group));
                                break;
                case 2: DisplayPack2(& (*Group));
                                break;
                case 3: DisplayPack3(& (*Group));
                                break;
                case 4: DisplayPack4(& (*Group));
                                break;
  default: printf("ERROR: Invalid package number.\n");
        }
}

//Definition of function DisplayPack1.
//Uses a constant Reservation reference parameter to hold the vacation package information.
//This function displays the information stored for vacation package 1.

void DisplayPack1(const struct Reservation *Group)
{
  printf("Number in party: %d\n", (*Group).Packs.Climb.Num);
        printf("Base charges: $%.2f\n", (*Group).Packs.Climb.BaseCharges);
        printf("Instruction Cost: $%.2f\n", (*Group).Packs.Climb.Instruction);
        printf("Equipment Rental: $%.2f\n", (*Group).Packs.Climb.Equipment);
        printf("Discount: $%.2f\n", (*Group).Packs.Climb.Discount);
        printf("Total Charges: $%.2f\n", (*Group).Packs.Climb.Charges);
        printf("Required Deposit: $%.2f\n", (*Group).Packs.Climb.Deposit);
}

//Definition of function DisplayPack2.
//Uses a constant Reservation reference parameter to hold the
//vacation package information.This function displays the information
//stored for vacation package 2.

void DisplayPack2(const struct Reservation *Group)
{
  printf("Number in party: %d\n", (*Group).Packs.Scuba.Num);
        printf("Base charges: $%.2f\n", (*Group).Packs.Scuba.BaseCharges);
        printf("Instruction Cost: $%.2f\n", (*Group).Packs.Scuba.Instruction);
        printf("Discount: $%.2f\n", (*Group).Packs.Scuba.Discount);
        printf("Total Charges: $%.2f\n", (*Group).Packs.Scuba.Charges);
        printf("Required Deposit: $%.2f\n", (*Group).Packs.Scuba.Deposit);
}

//Definition of function DisplayPack3.
//Uses a constant Reservation reference parameter to hold the
//vacation package information.This function displays the information
//stored for vacation package 3.

void DisplayPack3(const struct Reservation *Group)
{
  printf("Number in party: %d\n", (*Group).Packs.Sky.Num);
        printf("Base charges: $%.2f\n", (*Group).Packs.Sky.BaseCharges);
        printf("Lodging: $%.2f\n", (*Group).Packs.Sky.Lodging);
        printf("Discount: $%.2f\n", (*Group).Packs.Sky.Discount);
        printf("Total Charges: $%.2f\n", (*Group).Packs.Sky.Charges);
        printf("Required Deposit: $%.2f\n", (*Group).Packs.Sky.Deposit);
}

//Definition of function DisplayPack4.
//Uses a constant Reservation reference parameter to hold the
//vacation package information.This function displays the information
//stored for vacation package 4.

void DisplayPack4(const struct Reservation *Group)
{
  printf("Number in party: %d\n", (*Group).Packs.Spel.Num);
        printf("Base charges: $%.2f\n", (*Group).Packs.Spel.BaseCharges);
        printf("Equipment Rental: $%.2f\n", (*Group).Packs.Spel.Equipment);
        printf("Discount: $%.2f\n", (*Group).Packs.Spel.Discount);
        printf("Total Charges: $%.2f\n", (*Group).Packs.Spel.Charges);
        printf("Required Deposit: $%.2f\n", (*Group).Packs.Spel.Deposit);
}

---

A floating-point constant literal has type double. Try this:

Code:

---

float somevar = 0.00f; /* Note the f, that makes it float */

---

Or you could just eschew float and use double everywhere unless you have a need for single precision.

Basically a double is 64-bits wide and a float is 32. So when you convert from 64-bit data type to a 32-bit you lose a possible 32-bits of information. Unless you are trying to send a rocket to the moon or something this probably won't cause miscalculations. However, you can turn the warning off using one of the #pragma statements prior to the conversion. Check your docs for more info.

You don't need the #include <iostream.h> and most c programmers don't use 1 line comments ex:

Code:

---

//this is a one line commen
they prefer this
/*this is a one line(or multi-line commen)*/

---

the one line comment is c99 standart and I personally don't like c99, but I guess it is opinionated