Chapter 24 - Intro to Pointers created by s3f - https://repl.it/EyR4/10

Chapter 24 - Intro to Pointers.c

//                           Pointers

/* 
Inside your computer is a bunch of memory which holds your program as it executes as well as the variables you declare. Just as your house has a unique address, so does a memory location. 

Here are the pointer operators: & --> Address of operator 
                                * --> Dereferencing operator 
                                

Here's how you define an integer and floating point variable: 

  int num; 
  float value; 
  
Now here's how you define an integer pointer variable and a floating point pointer variable : 

int * pNum; --> Defines 2 pointer variables 
float * pValue

example code: 
              int age = 19; --> Stores a 19 in age 
              int * pAge = &age; Tells C to put the address of age into pAge 
              
Now the dereferencing operator mainly exists to tell C that the variable is a pointer, not a regular variable. 

Dereferencing simply means that you use the pointer to get to the other variable

The following program below that declares integer, float, and character variables, as well as pointer versions of all 3: 
*/



#include <stdio.h>

main()
{
    int kids;
    int* pKids;
    float price;
    float* pPrice;
    char code;
    char* pCode;

    price = 17.50;
    pPrice = &price;

    printf("\nHow many kids are you taking to the water park? ");
    scanf(" %d", &kids);

    pKids = &kids;

    printf("\nDo you have a discount ticket for the park? ");
    printf("\nEnter E for Employee discount, S for Sav- More ");
    printf("Discount, or N for No Discount ");
    scanf(" %c", &code);

    pCode = &code;

    printf("\nFirst let's do it with the variables: \n");
    printf("You've got %d kids...", kids);
    switch (code)
    {
        case ('E'):
            printf("The employee discount saves you 25% on the ");
            printf("$%.2f price", price);
            printf("\nTotal ticket cost: $%.2f", (price * .75 * kids));
            break;

        case ('S'):
            printf("The Sav-more discount saves you 15% on the ");
            printf("$%.2f price", price);
            printf("\nTotal ticket cost: $%.2f", (price * .85 * kids));
            break;
        default: // Either entered N for No Discount or an invalid letter

            printf("You will be paying full price of ");
            printf("$%.2f for your tickets", price);
    }

    // Now we repeat the same code but use dereferenced pointers instead

    printf("\n\n\nNow let's do it with pointers: \n");
    printf("You've got %d kids...", *pKids);
    switch (*pCode)
    {
        case ('E'):
            printf("The employee discount saves you 25% on the ");
            printf("$%.2f price", *pPrice);
            printf("\nTotal ticket cost: $%.2f", (*pPrice * .75 * *pKids));
            break;

        case ('S'):
            printf("The Sav-more discount saves you 15% on the ");
            printf("$%.2f price", *pPrice);
            printf("\nTotal ticket cost: $%.2f", (*pPrice * .85 * *pKids));
            break;
        default: // Either entered N for No Discount or an invalid letter

            printf("You will be paying full price of ");
            printf("$%.2f for your tickets", *pPrice);
    }
    return (0);
}