Problems with arrays

Question

I know this is going to be something of a silly slip or oversight on my behalf, but I can't get the array in this to print out correctly. When I run the code and put in my inputs, I get seemingly random numbers. For example, number of rooms was 1 wattage of lights was 2 hours used was 2 TV/computers was 2

The output I got was 3930804. What did I miss?

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

int main()
{
    int room[20] = {0.0};
    int i;
    int rooms = 0;
    char option = 0;
    int lights[20]; 
    int hrsUsed[20]; 
    int Telly_Computer[20];

    printf("Enter number of rooms");
    scanf_s("%d", &rooms);


        for(i=0;i<rooms;i++)
    {
        printf("input wattage of lights");
        scanf_s("%d", (lights+i));
        printf("input number of hours use/day (average)");
        scanf_s("%d", (hrsUsed+i));
        printf("input number of TV/Computers");
        scanf_s("%d", (Telly_Computer+i));
    }

        printf("%d \n", lights);

}

You're not doing any of your scanf_s right.

nhgrif
– nhgrif

2013-11-11 00:08:52 +00:00
Commented Nov 11, 2013 at 0:08 — nhgrif
– nhgrif, Commented Nov 11, 2013 at 0:08

sandymatt · Accepted Answer · 2013-11-11 00:08:58Z

1

printf("%d \n", lights);

You're printing the array directly. You need to loop over it and print the elements one at a time.

int i;
for (i = 0; i < 20; ++i)
  printf("%d\n", lights[i]);

answered Nov 11, 2013 at 0:08

sandymatt

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Comments

LeatherFace · Accepted Answer · 2013-11-11 00:17:11Z

1

You are just printing the address of lights (and using UndefinedBehavior by the way, address must be printed with %p). You must use a loop to print out all of the contents of each array slot.

for(int i=0;i<(sizeof(lights)/sizeof(int));i++)
    printf("%d\n",lights[i]);

edited Nov 11, 2013 at 0:17

answered Nov 11, 2013 at 0:10

LeatherFace

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1 Comment

sandymatt Over a year ago

sizeof(lights) will return the number of bytes in teh array. need to divide it by sizeof(int)

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