How to loop through allocated memory with pointer arithmetic C

Question

In order to loop through a regular int array with pointer arithmetic looks like such:

 int *p;
 int arraySize = 20;

 int array[arraySize];     

 for (p = array; p< array+(sizeof(array)/sizeof(int)); p++){
    int random = rand() % 200;
    *p = random;
  }

 for (p = array; p< array+(sizeof(array)/sizeof(int)); p++){
    printf("%d\t%x\n", *p, p);
  }



 for (p = array; p<array+(sizeof(array)/sizeof(int)); p++){
        int random = rand() % 200;
        *p = random;
  }

 for (p = array; p< array+(sizeof(array)/sizeof(int)); p++){
        printf("%d\t%x\n", *p, p);
  }

However, I want to declare:

int *array = (int*) calloc(arraySize, sizeof(int));

I am very confused on how to loop through dynamically allocated memory as opposed to a regular static array.

Replace every (sizeof(array)/sizeof(int)) with arraySize and both should function as you desire. — WhozCraig
– WhozCraig, Commented May 8, 2017 at 20:00

Meccano · Accepted Answer · 2017-05-08 19:41:36Z

2

int *array = (int*)calloc(arraySize, sizeof(int));
int *array_end = array + arraySize;
int* ptr;
for(ptr = array; ptr < array_end; ptr++)
    printf("%p\t%d", ptr, *ptr);

answered May 8, 2017 at 19:41

Meccano

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1 Comment

The Fool Over a year ago

code only answers are not all that useful. Please try to add some explaination.

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