pointer variable to integer?

Hi,

My problem is that I have an array stored in a file which contains a variable "type".

An example of the file is

1
Mr Blank
2 Blank Road
Blanksville
r

the final character 'r' stands for remove and is can be identified tbp->entry[j].type

what I am trying to do is read each record from the file and depending on the 'type' perform certain actions.

My code looks something like this

for(j=o; j<(tbp->n); j++)
if(tbp->entry[j].type == 'r')
statements;
else statements;

the problem seems to be that tbp->entry[j].type is not recognised as an integer and as such cannot be compared with 'r'

hope someone can help?

Andy

I assume that yourstruct.type is defined as a char *, but without you posting the definition of your structure this is conjecture.

A couple of solutions

o if the operation field in your file is only ever 1 character, then you don't need a pointer to a string for that field... a plain old char would do.

o use strcmp() instead of an == comparison (which you should do for all strings, unless you really do want to compare two pointers rather than the strings those pointers point to).

Ian Woods

How does tbp-> fit into the picture? If you have a struct like this:

struct Entry
{
int orderNumber;
char name[30];
char address[30];
char type;
}

Then you could have an array (or some other container) of type Entry like this to store the Entry's in the file.

const int SIZE;
Entry dataBase[SIZE];

Then you can read the entries into the array using one of several techiques (here's just one way);

while(!fin.eof())
{
for(int i = 0; i < SIZE; i++)
{
fin >> dataBase[i].orderNumber;
.
.
.
fin >> dataBase[i].type;
}
}

Then you could display the contents of the contaner:
for(int i = 0; i < SIZE; i++)
{
if(dataBase[i].type != 'r')
{
cout << dataBase[i].name << endl << dataBase[i].address << endl << endl;
}
}

or whatever.

Hi,

Thanks for all input.

Okay here's some of my coding to help explain the problem a little further.


#define TYPE_SIZE 2
/*Struct definitions...*/
struct transaction_book_element


{
char mem_num[MEM_NUM_SIZE];
char name[NAME_SIZE];
char addressone[ADDRESS_SIZE];
char addresstwo[ADDRESS_SIZE];
char type[TYPE_SIZE];
};
typedef struct transaction_book_element Transaction_Book_Element;
struct transaction_book


{
Transaction_Book_Element entry[TRANSACTION_BOOK_SIZE];
int n;
};


/* Here's some more of my definitions */

FILE *fp =fopen("tbfile.txt","r");
Transaction_Book *tbp,tb;
tbp = &tb;

I have tried using a string compare function resulting in the Error "comparrison of incompatible types "

I wondered if it would be possible to declare a pointer variable and assign a type action eg "r" to it then simply compare the two pointers but it dose'nt seem to work?

Please advise this troubled beginner?

PS I am working with a gcc compiler on a UNIX terminal so no C++ replies please. (I know C & C++ are similar but I'm only a beginner!).

Thanks again!

given those definitions, tbp->entry[i].type should be an array of char with TYPE_SIZE number of elements. It is not possible to use the == operator on arrays. You have to compare each individual element of the array, or one of the strcmp() family of functions if the array is really a string. Basically type is not an int, but a group of ints (ANSI char values). If type is a string then you shoulc be able to do this:

int result = strcmp(tbp->entry[i].type, "r");
if(result == 0)
....