Number of digits in an array?

[turke92]

How can I find out which digit appears the most in the array?
Here is something I tried, but really messed something up...

#include <stdio.h>
#define MIN 1
#define MAX 99


int main(){


int polje[10],znamenke[10]={0};
int i,j,prva,druga,max;


srand (time(0));


for (i=0;i<10;i++)
    polje[i] = MIN + rand()%(MAX-MIN+1);


for (i=0;i<10;i++)
    printf ("%d ",polje[i]);


for (i=0;i<10;i++){
    if (polje[i]>9)
    {
    prva = polje[i]/10;
    druga = polje[i]%10;
    znamenke [i] = znamenke[prva]++;
    znamenke[i] = znamenke[druga]++;
    }
    else znamenke[i] = i++;
}


max = znamenke[0];


for (i=1;i<10;i++)
    if (znamenke[i]>max) max = znamenke[i];


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


return 0;
}

[Adak]

1) declare an array of int's equal to the range of your data

2) for every number in the array, peel off the right hand digit, one by one, until there are no more digits left. As you peel them off, increment the INDEX of a digit_count[] array, with 10 places in it.

3) If the digit you peel off is a 3, then

digit_count[3]++;

etc.

The peel off is done with first number % 10 (effectively getting the one's column digit value), and then number / 10 (effectively removing the one's digit from the number.

Between the % 10 and the division by 10, that's where you want to do the counting. In rough code:

n = 123
while(n>0) {
   n2 = n % 10
   digit_count[n2]++
   n /= 10
}

[turke92]

Thanks!

[turke92]

for (i=0;i<10;i++){    while(polje[i]>0) {
        pom = polje[i] % 10;
        znamenke[pom]++;
        polje[i] /= 10;
        }
}


max=0;
for (i=0;i<10;i++)
    if (znamenke[i]>max) max = i;


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

I messed something up again but I can't see where the problem is...

[laserlight]

What is the whole of your current code? Please indent it properly.

[turke92]

Here is the whole code...
I don't get where I'm going wrong with indention... All the time I hear complaints but noone actually says where I went wrong...

#include <stdio.h>
#define MIN 1
#define MAX 99


int main(){


int polje[10],znamenke[10]={0};
int i,pom,max=0;


srand (time(0));


for (i=0;i<10;i++)
    polje[i] = MIN + rand()%(MAX-MIN+1);


for (i=0;i<10;i++)
    printf ("%d ",polje[i]);


for (i=0;i<10;i++){
    while(polje[i]>0) {
        pom = polje[i] % 10;
        znamenke[pom]++;
        polje[i] /= 10;
        }
}


for (i=0;i<10;i++)
    if (znamenke[i]>max) max = i;


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


for (i=0;i<10;i++)
    printf ("%d ",znamenke[i]);


return 0;
}

[laserlight]

Fair enough. Here is how I might format your program:

#include <stdio.h>

#define MIN 1
#define MAX 99

int main() {
    int polje[10], znamenke[10] = {0};
    int i, pom, max = 0;

    srand(time(0));

    for (i = 0; i < 10; i++)
        polje[i] = MIN + rand() % (MAX - MIN + 1);

    for (i = 0; i < 10; i++)
        printf("%d ", polje[i]);

    for (i = 0; i < 10; i++) {
        while (polje[i] > 0) {
            pom = polje[i] % 10;
            znamenke[pom]++;
            polje[i] /= 10;
        }
    }

    for (i = 0; i < 10; i++)
        if (znamenke[i] > max)
            max = i;

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

    for (i = 0; i < 10; i++)
        printf("%d ", znamenke[i]);

    return 0;
}

This is what my compiler reported:

test.c: In function `main':
test.c:10: warning: implicit declaration of function `srand'
test.c:10: warning: implicit declaration of function `time'
test.c:13: warning: implicit declaration of function `rand'

That is, you forgot to #include <stdlib.h> and <time.h>

EDIT:
Looking more carefully at your code, I think that you may have a fundamental misunderstanding about your requirements. You say that you are supposed to find which digit in the array appears the most often. Does this mean the array is supposed to be an array of digits?

[turke92]

I'm using GNU compiler and it didn't report anything but I will include them... Thanks for the tips!
Have you found the problem?

[turke92]

In case you don't understand what I'm talking about here is an example:

79 95 77 64 89 72 39 83 26 99
7 -> the digit that appears the most isn't 7! It's 9...

Control print:
0 0 2 2 1 1 2 4 2 6

[laserlight]

Have you found the problem?

I made an edit, but let me ask again: is the array supposed to be comprised only of digits?

For example:

{111, 2, 2}

The digit 1 appears most often, but the number 2 appears most often. What exactly are you trying to find?

EDIT:
Oh, okay. The problem is that you have a bug with your max finding code:

for (i = 0; i < 10; i++)
    if (znamenke[i] > max)
        max = i;

By comparing znamenke[i] with max, you are using max as a value to be compared to an element's value. By assigning i to max, you are using max as the index of an element.

[turke92]

I'm trying to find the DIGIT that appears most often... I'm sorry if I said otherwise!

EDIT:

for (i=0;i<10;i++) if (znamenke[i]>znamenke[max])
max = i;

I tried this and now it works perfectly! Thank you for your time!