C++ problem arrays?

cant get this to compile is there any way to do this


#include %26lt;iostream.h%26gt;





int main()





{


int count[9],n,i;











// sets number of sales user will enter





cout %26lt;%26lt; "/n Please enter how many salaries you would like to enter: ";


cin %26gt;%26gt; n;


int *n_ptr = %26amp;n; /sets pointer for memeory allocation





// gets sale input from customer








double sales[n_ptr];


for (i= 0; i %26gt; n; ++i)


{


cout %26lt;%26lt; "/n/n Please enter sales totel " %26lt;%26lt; endl;


cin %26gt;%26gt; sales[i];


}





// computes salaries


n = 1;





int saleries[n_ptr];





for (i=0 ; i %26gt; n; ++i)


{


int saleries[i] = 200 + sales[i]*.09;


}











return 0;





}

C++ problem arrays?
1) You coded: for (i= 0; i %26gt; n; ++i)





Should the condition be "i %26lt; n"? (And not "i %26gt; n")





2) You coded:





a) double sales[n_ptr];


b) int saleries[n_ptr];





Why are you declaring the arrays using an integer's address? Shouldn't you first de-reference the pointer, and then instead use the value that is stored at that address?





Instead, code should read:





a) double sales[*n_ptr];


b) int saleries[*n_ptr];
Reply:In your code problem starts here:


double sales[n_ptr];





Above statment is incorrect both syntactically %26amp; logically. First n_ptr is an memory address not an integer value(u could have replaced that with n or *n_ptr). Also, when u declare a static array, u have to use a fixed size say 100 etc.(e.g. sales[100])





Here size of sales array is not known at compile time so u will have to use dynamic memory allocation.








double * sales[n] =NULL; // Pointer , initialize to nothing.





sales = new double[n]; // Allocate n ints and save ptr in sales.


for (int i=0; i%26lt;n; i++) {


sales[i] = 0; // Use as an normal array.


}


. . . // Use as a normal array


delete [] sales; // When done, free memory


slaes = NULL; // Clear to prevent using invalid memory reference.





Also, correct this statement:


for (i= 0; i %26gt; n; ++i)


It should be i%26lt;n
Reply:#include %26lt;iostream%26gt;





using namespace std;





int main()





{


int n,i;


cout %26lt;%26lt; "Please enter how many salaries you would like to enter: ";


cin %26gt;%26gt; n;


double *sales = new double[n];


for (i=0; i%26lt;n; i++) {


cout %26lt;%26lt; "Please enter sales total: ";


cin %26gt;%26gt; sales[i];


}


// computes salaries


int *salaries = new int[n];





for (i=0; i%26lt;n; i++) {


salaries[i] = (int) (200. + sales[i] * .09);


}





// display


for (i=0; i%26lt;n; i++) {


cout %26lt;%26lt; "sale" %26lt;%26lt; i %26lt;%26lt; "=" %26lt;%26lt; sales[i] %26lt;%26lt; ", ";


cout %26lt;%26lt; "salary" %26lt;%26lt; i %26lt;%26lt; "=" %26lt;%26lt; salaries[i] %26lt;%26lt; endl;


}





delete[] sales;


delete[] salaries;





return 0;


}