The University of Iowa
The College of Liberal Arts and Sciences
Department of Computer Science
Lecture/Lab #7
Compound assignment, increment/decrement, control flow
What's the difference between x && y and x & y?
What will be the output of the following program?
int main() {
std::cout
<< std::boolalpha
<< !( 2 > 4 )
<< "\n";
}What does the x << y expression do?
x = x + n;
x = x - n;
x = x * n;
x = x / n;
x = x % n;
x = x & n;
x = x | n;
x = x ^ n;
x = x << n;
x = x >> n;x += n;
x -= n;
x *= n;
x /= n;
x %= n;
x &= n;
x |= n;
x ^= n;
x <<= n;
x >>= n;Is there a better way to express these?
Yes!
x += 1;
x -= 1;
Is there a better way to express these?
Yes!
++x;
--x;
OR...
x++;
x--;
Pre-increment and pre-decrement operators increment or decrement the value of the object and return a reference to the result
Post-increment and post-decrement create a copy of the object, increment or decrement the value of the object and return the copy from before the increment or decrement
if ( <condition> ) <statement> [else <statement>]
do <statement> while ( <condition> )
while ( <condition> ) <statement>
for ( <init-statement>; <condition>; <expression> ) <statement>
switch ( <condition> ) {
( ( case <constant> | default ): <statement> )+
}
if ( <condition> ) <statement> [else <statement>]
// the product of an integer and
// all the integers before it
int factorial( int n )
{
if ( n == 0 )
return 1;
else
return n * factorial( n - 1 );
}
Conditionally executes the first or the second statement.
Write a program that asks user for a number and prints "Yay" or "Nay" depending on the condition
Open the exercise template
Write your code, press Run to test
When you're done, grab your Repl's link and send it as a direct message to me (agurtovoy)
Click on the corresponding option in the "Lab7 exercises" poll in #general
while ( <condition> ) <statement>
// the product of an integer and
// all the integers before it
int factorial( int n )
{
int result = 1;
while ( n > 0 )
{
result = result * n;
n = n - 1;
}
return result;
}
Executes statement repeatedly, until condition becomes false. The condition is tested before each iteration.
int prompt_for_positive()
{
int n = -1;
do
{
std::cout << "Enter a positive number: ";
std::cin >> n;
}
while ( n <= 0 );
return n;
}
do <statement> while ( <condition> )
Executes statement repeatedly, until condition becomes false. The condition is tested after each iteration.
Write a program that asks user for a positive integer and prints out all the integers between zero and the input
( [0, input) )
Open the exercise template
Write your code, press Run to test
When you're done, grab your Repl's link and send it as a direct message to me (agurtovoy)
Click on the corresponding option in the "Lab7 exercises" poll in #general
#include <iostream>
int main()
{
for ( int i = 0; i < 10; ++i )
std::cout << i << " ";
}
Executes init-statement once, then executes statement and expression repeatedly, until the condition becomes false. The condition is tested before each iteration.
for ( <init-statement>; <condition>; <expression> ) <statement>
Open the exercise template
Write your code, press Run to test
When you're done, grab your Repl's link and send it as a direct message to me (agurtovoy)
Click on the corresponding option in the "Lab7 exercises" poll in #general
Write a program that asks user for a positive integer and uses `for` loop to print out all the even numbers between zero and the input
char c = 0;
std::cin >> c;
switch ( c )
{
case 'y':
case 'Y':
return true;
case 'n':
case 'N':
return false;
default:
return default_;
}
switch ( <condition> ) {
( ( case <constant> | default ): <statement> )+
}
Transfers control to one of the several statements, depending on the value of condition.
Write a program that asks user to make a selection from three items and uses `switch` statement to print out the selected item
Open the exercise template
Write your code, press Run to test
When you're done, grab your Repl's link and send it as a direct message to me (agurtovoy)
Click on the corresponding option in the "Lab7 exercises" poll in #general