#include <iostream.h>
#include <fstream.h>
#include <string.h>
#include <iomanip.h>

//for logfile
struct log
{
long number;
char date[9];
char time[9];
char gate[2];
};

//for customers
struct customer
{
long number;
char initial[2];
char lname[20];
char snumber[7];
char sname[17];
char stype[17];
char suburb[17];
char state[4];
char postcode[5];
};

//constants for array sizes
const int MAXLOGS=50;
const int MAXCUST=20;


// function protoytpes
int searchProcessed(long[],long,int);//searches already processed records
int find (customer[],long,int); //searches customer array
void showHeadings(); //show headings
void drawline(); //draws line

int main ()
{
//declare array to hold logs
log logArray[MAXLOGS];

//declare infile stream and link to log.txt
ifstream in;
in.open("log.txt");

int numOfLogs = 0; // number of logs

//load-up array with logs
while(!in.eof())
{
in >> logArray[numOfLogs].number;
in >> logArray[numOfLogs].date;
in >> logArray[numOfLogs].time;
in >>logArray[numOfLogs].gate;
in >> ws;
numOfLogs++;
}
in.close();

//declare array of type customer
customer customerArray[MAXCUST];
//open the file
in.open("customer.txt");


int numberOfCustomers = 0; //number of customers

//load-up array with customers
while(!in.eof())
{
in >> customerArray[numberOfCustomers].number;
in >> customerArray[numberOfCustomers].initial;
in >> customerArray[numberOfCustomers].lname;
in >> customerArray[numberOfCustomers].snumber;
in >> customerArray[numberOfCustomers].sname;
in >> customerArray[numberOfCustomers].stype;
in >> customerArray[numberOfCustomers].suburb;
in >> customerArray[numberOfCustomers].state;
in >> customerArray[numberOfCustomers].postcode;
in >> ws;
numberOfCustomers++;

}
in.close();

//declare array of type long, to hold custNumbers of
//previously processed records
long processed[MAXLOGS];
//initialize to zero
for (int i=0;i<MAXLOGS;i++)
{
processed[i]=0;
}
int processedSize=0;//nothing in array yet

// required heading
cout << "\t\tThis is the HEADING of the statement\n" << endl;

//main loop to process records
//processing the log array from first to number of logs
for ( int z = 0; z < numOfLogs; z++ )
{
//if current customer number has not been previously processed
if (searchProcessed(processed,logArray[z].number,numOfLogs) < 0)
{
//add customer number into array of previously processed records
processed[processedSize++] = logArray[z].number;

// find the position of the customer in customer array
// by searching with current customer number from log array
int position = find(customerArray,logArray[z].number,numberOfCustomers);

//if customer is found
if (position >=0)
{
drawline(); //draw a line

cout << "\nEWAY BILL E-way Motorway\n"
<< " " << customerArray[position].number;
cout << "\n \n"<<customerArray[position].lname <<customerArray[position].initial;
cout << " \n"<< customerArray[position].snumber <<customerArray[position].sname <<customerArray[position].stype;
cout << " \n"<<customerArray[position].suburb <<customerArray[position].state <<customerArray[position].postcode;
cout << "E-way motor bill for: "<<customerArray[position].number << endl << endl;
} // end printcustomerstatement

double total = 0.0;//accumulator for totals
showHeadings(); //show headings
drawline(); //draw a line

//from current position of log array to number of logs
//trying to process every entry of customer in the log file
for (int l = z ;l<numOfLogs;l++)
{

//if found an entry matching current customer number
//(first entry is always processed).
//processSize is -1 because it has been incremented above
if(processed[processedSize-1] == logArray[l].number)
{
//display detail line
cout <<setw(8) << logArray[l].date
<<setw(9)<< logArray[l].time
<<setw(8)<< logArray[l].gate;

//checking for toll-gate code
//adding to total for correct amount
//"case of" not used because 'gate' is of type char[]
//not int.
if(! strcmp(logArray[l].gate,"A") )
{
cout <<setw(7)<< "$2.20";
total = total + 2.20;
}
else if(! strcmp(logArray[l].gate,"B") )
{
cout <<setw(7)<< "$2.80";
total = total + 2.80;
}
else if(! strcmp(logArray[l].gate,"C") )
{
cout <<setw(7)<< "$3.30";
total = total + 3.30;
}
else
{
cout <<setw(7)<< "$3.80";
total = total + 3.80;
}
cout << endl;

}

}

cout << endl << setw(8)<<"DATE" <<setw(9) <<"TIME"
<< setw(8) << "STATION"
<< setw(7) << "AMOUNT"
<<endl;


// Function tollCharge

cout << endl << endl;
cout << "Total charge usage of E-way for:" << customerArray[position].number <<" "
<< " $" << setiosflags(ios::fixed)<<setprecision(2)<< total <<endl<<endl;

cout<<"\nEnd OF E-Way Statement";
return 0;
}


// searches the array for number and returns position if found
// else returns -1
int searchProcessed(long processed[], long num,int size)

{
for (int i = 0; i < size;i++)
{
if (num == processed[i])
return i;
}
return -1;
}


//searches customer array for number and returns position if found
//else returns -1
int find (customer customerArray[],long num ,int size)
{
for (int i=0;i<size;i++)
{
if ( num == customerArray[i].number)
return i;

}
return -1;
}
;
}
}

and what's wrong? (ie. does it not compile, or does it not work as you think it should?)

it doesnt compile .. but there an error

Three Great Virtues Of A Programmer
What's the error you see? It's much easier to check if you provide the compiler/linker messages. Also please put your program into [ code] tag, so that the formatting is preserved.

Also add what your program is supposed to do(a general idea) and put the compiler out put in [ c o d e ]