Thread: Assignment Problem (Structures)

Hi there! Basically, I have an issue understanding Question 1.

I need assistance with my functions "runElevators" and "goToFloor" as I'm not sure what is required in them. I think I did something wrong in "runElevators", but I'm not sure what exactly.

Any help would be greatly appreciated. Thanks!

Lab #5 (CS1010)

Code:

#include <stdio.h>#include <string.h>
#define CAPACITY 15
#define MAX_LEN 21
#define MAX_ELEVATORS 5


typedef struct { 
    int floor, passenger, usage;
} elevator_t;


void setupElevators(elevator_t [], int);
void readSequences(char [][MAX_LEN], int);
void runElevators(elevator_t [], char [][MAX_LEN], int);
void goToFloor(elevator_t *, int);
void printElevators(elevator_t [], int size);
int mostUsedElevator(elevator_t [], int);


// This function is given. You are NOT to modify it.
int main(void){
    int size;
    elevator_t elevators[MAX_ELEVATORS];
    char sequences[MAX_ELEVATORS][MAX_LEN];
    
    printf("Enter number of elevators: ");
    scanf("%d", &size);
    
    setupElevators(elevators, size);
    readSequences(sequences, size);
    
    runElevators(elevators, sequences, size);
    
    printElevators(elevators, size);
    printf("Most used elevator: %d\n", mostUsedElevator(elevators, size));
    
    return 0;
}


void setupElevators(elevator_t elevators[], int size){
    
    int i;


    for(i = 0; i < size; i++)
    {
        elevators[i].floor = 1;
        elevators[i].passenger = 0;
        elevators[i].usage = 0;
    }
}    


// Read in the sequences of floors the elevators go to.
// This function is given. You are NOT to modify it.
void readSequences(char sequences[][MAX_LEN], int size){
    int i;
    
    for (i = 0; i<size; i++){
        printf("Enter sequence for elevator %d: ", i+1);
        scanf("%s", sequences[i]);
    }
}


void runElevators(elevator_t elevators[], char sequences[][MAX_LEN], int size){
    
    
    int i, c;


    for(i = 0; i < size; i++)
        for(c = 0; c < strlen(sequences[i]); c++)
        {    
            elevators[i].floor = sequences[i][strlen(sequences[i]) - 1];
            
            if((elevators[i].passenger < 15) && (sequences[i][c+1] > sequences[i][c]))    
                elevators[i].passenger += sequences[i][c];


            if(elevators[i].passenger > 15)
                elevators[i].passenger = 15;
                
            if((elevators[i].passenger > 0) && (sequences[i][c] > sequences[i][c+1]))
                elevators[i].passenger -= sequences[i][c+1];
            
            if(sequences[i][c] > sequences[i][c+1])
                elevators[i].usage += sequences[i][c+1];
        }


}




/*void goToFloor(elevator_t *elevator, int floor){
    
     



       
void printElevators(elevator_t elevators[], int size){
    
    int i;


    for(i = 0; i < size; i++)
    {    
        printf("Elevator : %d\n", i+1); 
        printf("Floor: %d\n", elevators[i].floor);
        printf("Number of passengers: %d\n", elevators[i].passenger) ;
        printf("Usage: %d\n", elevators[i].usage);
    }
}


int mostUsedElevator(elevator_t elevators[], int size){
    // Incomplete
    return 1;
}

No wonder things are so terrible...

Code:

// This function is given. You are NOT to modify it.
int main(void){

// Read in the sequences of floors the elevators go to.
// This function is given. You are NOT to modify it.
void readSequences(char sequences[][MAX_LEN], int size){

And yet there is clearly a very high potential for a buffer overflow (two actually). But you're not allowed to fix either of them. Who wrote the skeleton program and the parts you're not allowed to change?

Originally Posted by laserlight

The functions have access to the MAX_ELEVATORS macro, so they can check if size > MAX_ELEVATORS, and if so ignore the invalid input by using MAX_ELEVATORS as the size, or maybe even terminate the program with an error message.

Of course they do. But the student is not allowed to modify the functions already implemented, or main().