Input/Output Main Memory istream ostream Disk Drive Keyboard Scanner Disk Drive Monitor Printer stream = sequence of bytes

Input/Output standard library Unformatted – stream of bytes. Good for high speed, high volume transfers Formatted – groupings of bytes. Integers, characters, etc.

iostream library - cin, cout, cerr an istream object named cin associated with the keyboard an ostream object named cout associated with the monitor an ostream object named cerr associated with the monitor

operators << stream insertion operator int grade = 5; cout << grade; >> stream extraction operator int grade; cin >> grade;

cout details int grade = 92; cout << grade; // causes 92 to be displayed on the screen 92 grade 4 bytes bytes integer char steps: 1)convert integer 92 to character sequence 92 2)send characters 9 2 to the screen

cout details cout << ‘9’ << ‘2’; // causes 92 to be displayed on the screen bytes char bytes char no conversion necessary cout knows what to do because it knows the data type

concatenation of stream operators int grade = 92; cout << “your grade is” << grade; is the same as: cout << “your grade is”; cout << grade;

cout escape sequences \ escape character. special character follows cout << “Hello \n”; \n newline \\ backslash \” double quote \t tab

stream manipulators endl – writes a newline, flushes buffer cout << “your grade is” << grade << endl; what’s a buffer ? place to hold data while waiting for I/O operation to complete. 1 second = 1000 milliseconds = 1 million microseconds cout << grade; // microseconds to execute // milliseconds or seconds to complete I/O 29 cout puts things in i/o device takes things out first in first out buffer

stream manipulators double veryPreciseNumber = ; cout << veryPreciseNumber << endl; prints cout << setprecision(10) << veryPreciseNumber; prints #include //needed to use setprecision stays in effect for all subsequent cout calls setprecision(0) sets it back to default value

stream manipulators cout.setf(ios::showpoint); ios::hex Format numeric values as base 16 (hexadecimal). ios::showpoint Show decimal point and trailing zeros for floating-point values. ios::showpos Show plus signs (+) for positive values. ios::scientific Display floating-point numbers in scientific format. ios::fixed Display floating-point numbers in fixed format.

cout Exercises Identify the error in each of the following statements and explain how to correct it. 1) The following statement will print the integer value for ‘c’. cout << ‘c’; 2) cout << “”A string in quotes”” << endl; 3) display the number 200 with and without the + sign.

cin int age; cin >> age; operand to right of >> must be a variable nothing read until Enter key is typed reads input until end of input value is reached. 12 (age = 12) 1 2 (age = 1) input data must match data type. x would be an error for input for age.

cin concatenation okay int age, weight; cin >> age >> weight; Input: cin statement causes program to wait until input is entered. Should precede it with prompt cout << “Please enter age and weight”; handout on cin in Prof Hamel’s section of web site C++ How to program, Harvey Deitel Chapter 11

cin.get Useful when you want to be read whitespace characters i.e write a program to change a single spaced document into a double spaced document. char nextCharacter; cin.get (nextCharacter);

For each question, assume the following declarations: int num1, num2, num3; double real1, real2, real3; Each question is separate. 1) cin >> num1 >> num2 >> num3; INPUT ) cin >> real1 >> real2 >> real3; INPUT ) cin >> num1 >> num2 >> num3; INPUT ) cin >> num1 >> real1 >> num2 >> real2 >> num3 >> real3; INPUT cin Exercises