Galton Box/Bean Machine-C - c

Question

I want to code a simple bean machine program. The program will accept user input for the number of balls and the number of slots, and will calculate the path of each ball. The number of balls in each slot will be printed as a histogram as well.
I tried my best to keep the code short and sweet, yet the best I have managed is 112 lines long. When I ran my code, I received no errors. However, the output seems to have run into some sort of an infinity loop (The '#' symbol which was used to represent numbers in the histogram keeps on printing forever for some reason unknown to me).
Apparently, there is something wrong with my logic somewhere... or a silly little mistake in syntax(but it would have shown up as error, wouldn't it?)... In a nutshell, I cannot figure out exactly what is the problem. (I attempted to walk through the whole code process from start to finish, but my mind kept getting tangled up somewhere in the middle of the code, nowhere near the end of the code either).
Where exactly does my logic go wrong?(Or have I taken the wrong approach to the whole problem?) I do not wish to know the correct code, so that I am able to learn during the whole process of re-editing my code.
Any help (hopefully no model-code answers though), even as a single comment, is tremendously appreciated! :)
This is my code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <conio.h>
#include <stdbool.h>
#include <time.h>
//Pls excuse my extensive use of libraries even though I don't really use them
int intchecker(float x)
{
if (floor(x)==x && ceilf(x)==x)
{
return 0;
}
else {
return 1;
}
}
int main(){
char line[] = " +----+----+----+----+----+----+----+----+----+----+---+";
char numbers[] = " 0 5 10 15 20 25 30 35 40 45 50";
float balls,slots;
int slotarry[9],tlevel,ballnum,column,lcounter=0,slotsduplicate=1,y;//tlevel-number of levels in the triangle
srand(time(NULL));
int r;
printf("==========================================================\nGalton Box Simulation Machine\n==========================================================\n");
printf("Enter the number of balls [5-100]: ");
scanf("%f",&balls);
while (balls>100 || balls<5) {
printf("\nInput is not within the range. Please try again.");
printf("\nEnter the number of balls [5-100]: ");
scanf("%f",&balls);
}
while (intchecker(balls)==1) {
printf("\nInput is not an integer. Please try again.");
printf("\nEnter the number of balls [5-100]: ");
scanf("%f",&balls);
}
printf("Enter the number of slots [2-10] : ");
scanf("%f",&slots);
while (slots>10 || slots<2) {
printf("\nInput is not within the range. Please try again.");
printf("\nEnter the number of slots [2-10] : ");
scanf("%f",&slots);
}
while (intchecker(slots)==1) {
printf("\nHow can there be a fraction of a slot? Please re-enter slot number.");
printf("\nEnter the number of slots [2-10] : ");
scanf("%f",&slots);
}
tlevel=slots-1;
for(ballnum=1,column=0;balls>0;balls--,ballnum++,column++){
if (column%5==0){
printf("\n");
}
if (ballnum<10){
printf("[0%d]",ballnum);
}
else{
printf("[%d]",ballnum);
}
for(;tlevel>0;tlevel--){
r = rand() % 2;
if (r==0){
printf("R");
}
else {
printf("L");
lcounter++;
}
}
slotarry[lcounter]++;
tlevel=slots-1;
lcounter=0;
printf(" ");
}
printf("\n\n%s",numbers);
printf("%s",line);
char line2[] = "\n +----+----+----+----+----+----+----+----+----+----+---+";
for(;slotsduplicate<=slots;slotsduplicate++){
if (slotsduplicate<10){
printf("0%d|",slotsduplicate);
}
else{
printf("%d|",slotsduplicate);
}
y=slotarry[slotsduplicate];
if (y==0){
printf(" 0");
}
else{
for (;y>0;y--){
printf("#");
}
printf(" %d",slotarry[slotsduplicate]);
}
printf("%s",line2);
}
return 0;
}
Note:This is not completely error-free. This is just my first draft. I just wish to find out why there is an infinite loop.

Answer 1

Here's how I found the problem. First of all, I think it is a bit of a code smell to have a for loop without anything in the initial assignment section. Couple that with the fact that it seems to print # forever, and it looks like y has a garbage value at the beginning of the loop to print the #s.
So I ran your code in the debugger and paused it when it started printing loads of hashes. I checked the value of y and sure enough it was some unfeasibly high number.
Then I checked where y comes from and found you get it from slotarray. I printed it in the debugger and found that all the values in it were unfeasibly high or massively negative numbers. Obviously, slotarray wasn't being initialised correctly, so I looked for where it was initialised and bingo!
Stack variables (of which slotarray is one) must be explicitly initialised in C. I fixed your code with a call to memset.
The whole debugging process I have just outlined took something less than a minute.
ETA As #EOF points out, there is another bug in that slotarray is defined to contain nine slots (indexed 0 - 8) but you allow people to enter 10 slots. This is a buffer overflow bug.