Unable to print integer array

Question

Im a newbie to C, I primarily migrated/re-implemeted C programs to Java, etc. I'm trying to learn C and I have gone through several tutorials. I have a program that attempts to read user input(numbers) from command line via char *argv, sort those numbers and just print the sorted numbers out.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main (int argc, char *argv[])
{
        //if the is argument supplied
        if (argc > 1)
        {
            int count = 0;
            //array to sort less 1
            count = argc -1;
            int tobe_sorted[count];
            int i=0;
            //allocate memory for target result array
            int *target = malloc(count * sizeof(int));
            //copy unsorted ints to target
            memcpy(target, tobe_sorted, count * sizeof(int));
            //sort target using bubble sort
            int temp =0;
            int x =0;
            int y=0;
            for (x=0; x<count; x++ )
            {
                for (y=0; y<count -1; y++ )
                {
                    if (target[i]>target[i+1])
                    {
                        temp = target[i+1];
                        target[i+1] = target[i];
                        target[i] = temp;

                    }
                }//end inner

            }//end outer

            //end bubble sort
            x=0;
            printf("Sorted:\n");
            //print sorted array
            while (x <count)
            {
                printf("%d",target[x]);
                printf(",");
                x++;
            }
             printf("\n");
        }//end argument supplied
        else{
            printf("Error, please enter numbers to be sorted\n");
        }

        return 0;
    }//end main function

My input

PS C:\Users\xyz\workspace_cpp\the_hard_way\ex18> .\sort_test.exe 5 4 3 2 1

Output

Sorted:
2686748 1986196690 32 1 4199492

I'm not sure what C is printing out, are these ASCII codes?
What do I need to fix in the above program in order to print the sorted int array?

Disclaimer: Im not looking to use library functions such as qsort(), or to make the program more efficient.

Edited & working code based on comments (there is an extra index being allocated in target array, otherwise sorting & char to int conversion is working):

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main (int argc, char *argv[])
{
        //if thee is argument supplied
        if (argc > 1)
        {
            int count = 0;
            count = argc;
            int tobe_sorted[count-1];
            //initialize with 0's
            int i=0;
            for (;i<count; i++)
            {
                tobe_sorted[i] = 0;
            }
            //populate tobe_sorted with integer values of argv
            i=0;
            for (;i<count; i++)
            {
                tobe_sorted[i] = atoi(argv[i]);
            }

            //allocate memory for target result array
            int *target = malloc((count * sizeof(int)));
            //copy unsorted ints to target
            memcpy(target, tobe_sorted, count * sizeof(int));
            //sort target using bubble sort
            int tmp =0;
            int x =0;
            int y=0;
            int swapped = 1; 
            while (swapped)
            {
                swapped =0; 
                y++;
                for (x=0; x < count - y; x++)
                {
                    if (target[x] > target[x+1])
                    {
                        tmp = target[x];
                        target[x] = target[x+1];
                        target[x+1] = tmp;
                        swapped = 1; 
                    }
                }
            }
            //end bubble sort
            x=0;
            printf("Sorted:\n");
            //print sorted array
            while (x <count)
            {
                printf("%d",target[x]);
                printf(",");
                x++;
            }
             printf("\n");
        }//end argument supplied
        else{
            printf("Error, please enter numbers to be sorted\n");
        }

        return 0;
    }//end main function

Input:

PS C:\Users\xyz\workspace_cpp\the_hard_way\ex18> .\sort_test.exe 5 -3 -2 1 8

Output Sorted: -3,-2,0,1,5,8,

First thing is to decide if you're trying to learn C or C++, and get your tags right. — Jonathan Potter
– Jonathan Potter, Commented Jun 30, 2015 at 23:15
memcpy(target, tobe_sorted, count * sizeof(int)); looks wrong. tobe_sorted is uninitialized. Did you mean to use argv? Even if so, that would still be wrong. The argv values are strings not integers. You need to convert each argv string to an int with atoi or strtol. — kaylum
– kaylum, Commented Jun 30, 2015 at 23:16

John3136 · Accepted Answer · 2015-06-30 23:15:45Z

3

You never initialize target or tobe_sorted - they are "full of junk".

You never take the numbers off your command line argv and do anything with them.

You're going to need to convert the strings in argv into ints. Something like this:

for(i = 1; i < count; i++) {
    tobe_sorted[i-1] = atoi(argv[i]);
}

Before your memcpy()

answered Jun 30, 2015 at 23:15

John3136

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1 Comment

cyber101 Over a year ago

Sorry for horrible(idiotic) post , I was actually in a hurry , yes you & all other are all right, I fixed the issue & edited the post. Thanks.

Jack · Accepted Answer · 2015-06-30 23:17:35Z

2

The main problem here is that you are not using argv at all.

You declare an array named tobe_sorted, you don't initialize its values (so it contains garbage).

Then you copy the data on the target array and you sort that garbage data. Then you print them.

You must parse argv, convert each argument to an int using something like atoi and then sort these values.

answered Jun 30, 2015 at 23:17

Jack

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Comments

rost0031 · Accepted Answer · 2015-06-30 23:19:27Z

2

You have several problems:

int tobe_sorted[count];

This is uninitialized. It currently contains junk. You're then copying that junk to your target array.

//copy unsorted ints to target memcpy(target, tobe_sorted, count * sizeof(int));

As mentioned in 1, your tobe_sorted array doesn't contain your data. You want to parse *argv[], which is an array of arrays that contains the actual cmdline input. argc just tells you how many elements exist in *argv[] array. You need to parse the argv array, convert each element into an int and store the results in the tobe_sorted array.

answered Jun 30, 2015 at 23:19

rost0031

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