HOME-WORK FOR THE "ONE WEEK HOLIDAY"
NOTE
DOWN the following Key Points in DATA FILE HANDLING
:
Read( ) : A function used to
read a fixed number of bytes from the specified
file stream object and puts them in the
object passed as first argument.
General Syntax :
Straeam_object.read ( (char *)
&Oject , sizeof(Object));
Example :
………………… code………………..
EMPLOYEE emp; // an object/instance of class created
fstream f;
f.open(“EmpDetails.dat”,ios::in);//
an already xisting file containing employs details opened for reading
// if open succeeds then f contains NON-ZERO VALUE i.e. an address in main memory allocated for the //file object….if open fails f will be zero.
if(!f) {
cout<<” file can not be open—OPEN FAILED
“;
exit(1); //send FAILURE=1 MESSAGE
TO OPERATING SYATEM AND skip execution of the remaining part //of program.
}
While(!f.eof())
{ Cout<<”\n DETAIL OF
EMPLOYEES : \n”;
f.read((char*)&emp,sizeof(emp));
// SOURCE of data :
f TARGET : emp object
//first argument gives address
of object where we want to store data after retrieving form file f , second //argument
gives the number of UNITS of data to be copied form f to emp.
//(char *) tells that UNIT to be
used for counting is character/byte. [byte by byte copy operation ]
Emp.display(); //use display() public member func to
display one employee details
}
NOTE : Similarilly write() also works….. only
difference is in SOURCE and Target of
data
f.close();
f.open(“EmpDetails.dat”,ios::out
|ios::ate);
int flag=1;
while(flag)
{
emp.enter();
f.write((char*)&emp,sizeof(emp)); //one object writeen into file object at the
end of file
// SOURCE of data :
emp object TARGET
: f
cout<<”\n DO U WANT TO
CONTINUE …enter 0 to stop \n”;
cin>>flag;
} //data written to a file using write() can only be read
accurately using read ()
HOME ASSIGNMENT
[PART 1]
DATA FILE HANDLING :
Q1. What are
the general steps to be followed while writing a program to handle multiple
files in a program?
Q2. Write a prog. To count the
number of vowels present in a text file.
Q3. Write a prog. To calculate average word size of a text file.
Q4.write a prog. To count no. of
lines in a text file.
Q5.Write a prog to find out the
size of a file in bytes.
Q6.Write a prog to read and
write an object using read() and write() using binary file.
[PART 2] BOOLEAN ALGEBRA :
Q7. Draw a logical circuit diagram for the
following Boolean Expression :
X’.(Y’+Z)+Y.Z’+XQ8. Convert the following Boolean expression into its equivalent Canonical Sum of Product form –SOP:
(X’+Y+Z’).(X’+Y+Z).(X’+Y’+Z).(X’+Y’+Z’)
Q9. Simplify by using K-MAP :
F(A,B,C,D)=∑(0,1,2,4,5,7,8,9,10,11,14)
Q10. Simplify by using K-MAP :
F(A,B,C,D)= ∏(5,6,7,8,9,12,13,14,15)
Q11. Design NOT, AND ,OR gates using
(a) only NAND gate as basic gate
(b) using only NOR gate as basic gate
Q12. Verify XY’+X’Y+X’Y’ = (X’+Y’) using (a) Algebraic method
(b) Truth Table
Q13.Prove both DeMorgan’s theorems for 4 inputs- A, B , C
, D using (a) Algebraic method
(b) Truth Table.(we already know about
the 2-input DeMorgan’s theorems )
******************** THE END **********************
