update dynamically an array c code example

Example: c infiite array

int main(int argc, char *argv[])
   {
       int i;
    
       double* p;    // We uses this reference variable to access
   		     // dynamically created array elements
    
       p = calloc(10, sizeof(double) );  // Make double array of 10 elements
    
       for ( i = 0; i < 10; i++ )
   	  *(p + i) = i;            // put value i in array element i
    
       for ( i = 0; i < 10; i++ )
   	  printf("*(p + %d) = %lf\n", i, *(p+i) );
    
    
       free(p);      // Un-reserve the first array
    
       putchar('\n');
    
       p = calloc(4, sizeof(double) );  // Make a NEW double array of 4 elements    
      
       // ***** Notice that the array size has CHANGED !!! ****

       for ( i = 0; i < 4; i++ )
   	  *(p + i) = i*i;            // put value i*i in array element i
    
       for ( i = 0; i < 4; i++ )
   	  printf("*(p + %d) = %lf\n", i, *(p+i) );
    
       free(p);      // Un-reserve the second array
   }