将数字读入数组时，代码崩溃... C语言

Question

Hey my code crashed when I start to input data into the array. The program is supposed to read numbers into an array and then insert a new number into the array and at the ends it arranges everything in an ascending order. I am not sure what is wrong with it. anyone got suggestions?

Here is my code

#include <stdlib.h>
#include <stdio.h>
#define MAX 10000

int main() // Main
{

printf ("COP2220 - Project 5 - Manuel Ubau\n\n"); //Program Starts and Explains

printf ("This program inserts a number into an array in order of magnitude\n\n");

//Local Declarations
int i,j;
int n; //size of array
int x;
int arr[MAX]; //the arrays maximun 100 numbers
int pos;


printf("Please enter the size of the array: "); //Asks for size of array

scanf("%d",&n); //Reads size of array

   for(i=0;i<n;i++) // Reads values of the array
   {
    printf("Enter number for element #%d: ",i+1);
    scanf("%d",&arr[i]);
   }

printf("\nThe Original Array is:");  //Prints original Array for reference

    for(i=0;i<n;i++)
    {
      printf("\t%d",arr[i]);
    }


printf("\n\nEnter the value you want to insert into the arary: "); //Asks for X
scanf("%d",&x); //Reads number

     for(i=0;i<n;i++) // Determines position of the new number
     if(x<arr[i])
     {
       pos =i;
       break;
     }

     for(i=n;i>=pos;i--) //Displaces the array 1 space to the left so new number 
     arr[i]= arr[i-1];
     arr[pos]=x;       //Inserts the number into "pos" defined before

     for(i=0;i<=n;i++) // Arranges array
     {
      for(j=i;j<=n;j++)
         {
           if(arr[i] > arr[j])
             {
              int temp=arr[i];
              arr[i]=arr[j];
              arr[j]=temp;
             }
         }
      }

 printf("\nThe final array is:"); //Prints New array
   for(i=0;i<=n;i++)
   {
      printf("\t%d",arr[i]);
   }

printf("\n\nThanks!\n");
return 0; //Program Ends
}

Thanks in advance. Oh btw the program doesnt crash in any particular input number. It seems more like a random crash.

Edit: The crash happens when I input random numbers that I type. but if I do it in order, it doesnt crash. For example if I do an array of size 10 and its values is 1 2 3...10 it works perfectly but as soon as I use random numbers like 100 456 54... etc some times it crashes and some times it works. I havent determined a right sequence to make it crash. and there is no output, the program closes automatically and doesnt let me see if it printed something else or not

Answer 1

It crashes when you set a value bigger than any other value when you ask for a value to be inserted because pos is not initialised and it contains a random value (infact in that case x<arr[i] is never satisfied). You just need to initialise the pos properly (position n which is the next available one) before proceding

pos = n;
for(i=0;i<n;i++) { // Determines position of the new number
   if(x<arr[i])
   {
     pos =i;
     break;
   }
}

Note that you should also check that the user writes less than 10000 to the question related to the vector size (max 99 because you ask to add a number after) as size for the vector or you will have a buffer overflow there

Another error is in the loop. Let say that pos=0 is the correct pos.

for(i=n;i>=pos;i--) //Displaces the array 1 space to the left so new number 
   arr[i]= arr[i-1]; //pos (Copy pos-1)

In case in which pos is equal to 0 you try to copy arr[0]=arr[-1] that causes a crash. you need to do the loop as follows:

for(i=n;i>pos;i--) //Displaces the array 1 space to the left so new number 
   arr[i]= arr[i-1]; //pos (Copy pos-1)

So that the last copy is safe (arr[1]=arr[0]).