Thread: Simple coversion program hanging on input

Dear All,

I have written this programme that reads a set of n digits and converts them into a single decimal integer. For example if the input is an array of integers 2,3,4,12,4 then the output should be 234124. My program is hanging when I input a digit. Below is my code, please tell me the error:

Code:

#include<stdio.h>
int main()
{
    int *a,sum=0,i,n;
    printf("enter the number of digits");
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
           scanf("%d",&a[i]);
    }
    for(i=1;i<=n;i++)
    {
    printf("%d",a[i]);
    }
    system("pause");
    return 0;
}

Thank you for your reply.

Where are you allocating any memory for your variable a?

Note: Your compiler should be warning you about uninitialized variables. If you are not getting them you need to check your compiler settings and insure warnings are being generated, and select the highest level of warnings.

Jim

No need to use a pointer here, just declare a as array, with some max size that you want.

Problem solved using the method suggested by Stevan. I still wanted to keep the array size dynamic, so that when the user
can enter as many numbers as he/she wants.

@Jimblumberg - As far as allocating memory to variable 'a' is concerned, what if I assign the value 0 to *a and then input numbers. Could you show me how to dynamically allocate the memory? Thank you.

Originally Posted by jimblumberg

Where are you allocating any memory for your variable a?

Note: Your compiler should be warning you about uninitialized variables. If you are not getting them you need to check your compiler settings and insure warnings are being generated, and select the highest level of warnings.

Jim

To dynamically allocate memory in C you use malloc to allocate the memory. Here are a couple of links that should help explain how to use dynamic memory allocation in C: Advanced Memory Management: Dynamic Allocation, Dynamic Data Structures: Malloc and Free, and DYNAMIC ALLOCATION.

Don't forget to use malloc you must include stdlib.h.

Jim

Thank you for your prompt help.

Originally Posted by jimblumberg

To dynamically allocate memory in C you use malloc to allocate the memory. Here are a couple of links that should help explain how to use dynamic memory allocation in C: Advanced Memory Management: Dynamic Allocation, Dynamic Data Structures: Malloc and Free, and DYNAMIC ALLOCATION.

Don't forget to use malloc you must include stdlib.h.

Jim

Code:

#include<stdio.h>
#include<conio.h>

void main()
{
    long int num[10],i,a,sum=0;

   printf("enter the number of terms::");
   scanf("%ld",&a);

   for(i=0;i<a;i++)
   {
    printf("\nenter the %d element::",i+1);
      scanf("%ld",&num[i]);
   }

    for(i=0;i<a;i++)
    {
       if(num[i]<10)
       sum=sum*10+num[i];
         else
          sum=sum*100+num[i];
      }

   printf("\n the output is = %ld",sum);

    getch();
}