Saturday, December 16, 2006 “The whole of the development and operation of analysis are now capable of being executed by machinery… As soon as an Analytical Engine exists, it will necessarily guide the future course of science.” - Charles Babbage (1792 - 1871)
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Saturday, December 16, 2006
“The whole of the development and operation of analysis are now capable of being executed by
machinery… As soon as an Analytical Engine exists, it will necessarily guide the
future course of science.”
- Charles Babbage (1792 - 1871)
Office hours today
Another way of writing this? if(num_credits < 0)
{ cout << "Come on, get real" << endl; } else if (num_credits < 12) { cout << "Part-time student" << endl; } else if (num_credits < 18) { cout << "Full-time student" << endl; } else { cout << "Glutton for punishment" << endl; }
Nested if statements The <statements> inside the braces can contain any valid C++
statements, including if statements!
// … some other code here
char answer;
if (withdrawal > balance)
{ cout << "Insufficient funds." << endl; cout << "Do you want to see your balance? "; cin >> answer; if (answer == 'y') cout<< "Your balance is "<<balance<< endl; } else { cout << "Here is your money." << endl; } cout << "Good bye." << endl;
Nested if statements if (x>y){if (x>z)statement1;if (x>p)statement2;elsestatement3;}elsestatement4;//bad style- no indentation (code with proper indentation on next
slide)
Nested if statements if (x>y){
if (x>z) statement1;
if (x>p) statement2;
else statement3;
}else
statement4;
/*else statement always refers to nearest if statement that is within same block as else and not already associated with another else*/
Nested if statements // what is wrong here? int main(){int x=10, y=2, z=12, p=13;if (x>y){
if (x>z) cout<<1<<endl;//statement1;
if (x>p) cout<<2<<endl;//statement2;
else cout<<3<<endl;//statement3;else
cout<<4<<endl;//statement4;}else
cout<<5<<endl;//statement5;
return 0;}
Nested if statements // what is wrong here? int main(){int x=10, y=2, z=12, p=13;if (x>y){
if (x>z) cout<<1<<endl;//statement1;
if (x>p) cout<<2<<endl;//statement2;
else cout<<3<<endl;//statement3;else //Error
cout<<4<<endl;//statement4;}else
cout<<5<<endl;//statement5;
return 0;}
Nested if statements // what is output here? int main(){
int x=10, y=2, z=12, p=13;if (x>y){
if (x>z){cout<<1<<endl;//statement1;if (x>p)
cout<<2<<endl;//statement2;else
cout<<3<<endl;//statement3;}else cout<<4<<endl;//statement4;
}else
cout<<5<<endl;//statement5;return 0;
}
Output is 4
SELF TEST // what is wrong here? int main(){
int x=10, y=2, z=12, p=13;if (x>y){
if (x>z) cout<<1<<endl;//statement1;
if (x>p) cout<<2<<endl;//statement2;
else cout<<3<<endl;//statement3;
cout<<4<<endl;//statement4; }else
cout<<5<<endl;//statement5;
return 0;}
SELF TEST // what is wrong here? int main(){
int x=10, y=2, z=12, p=13;if (x>y){
if (x>z) cout<<1<<endl;//statement1;
if (x>p) cout<<2<<endl;//statement2;
else cout<<3<<endl;//statement3;cout<<4<<endl;//statement4; /*this statement is not in the above else block, it will always be executed whenever we enter if(x>y) block. Try this code for x=10, y=2, z=3, p=13 and also for x=10, y=2, z=13, p=3 */
}else
cout<<5<<endl;//statement5;return 0;}
char alarm;int fuel_quantity, temperature, pressure;cout<<"Enter alarm fuel_quantity temperature pressure\n";cin>> alarm >> fuel_quantity >> temperature>> pressure;if (alarm=='y'){
if(fuel_quantity <10){cout<<"Add more fuel\n";
}else{
if (temperature >90){if (pressure >100)
cout<<"RED ALERT! Shut down motor\n";else
cout<<"Turn on pressure valve\n";}else {
cout<<"Check temperature again after 10 minutes\n";}
}
}else {
cout<<"No problem with motor\n";}
Loops of various sorts are used to repeat a set of statements some number of times.
Print numbers from 0 to 1000
int count_down=3;
while (count_down > 0)
{ cout << "Hello "; count_down -= 1;
}
int count_down=3;
while (count_down > 0)
{ cout << "Hello "; //count_down -= 1;
}
What happens now?
int x = 10;
while ( x > 0)
{ cout << x << endl; x = x – 3;
}
int x = 10;
while (x > 0)
{ cout << x << endl; x = x – 3;
}Output using the comparison x < 0 instead of x > 0?
What happens here?
int x = 1;
while (x != 12)
{ cout << x << endl;
x = x + 2;
}
Print the odd numbers less than 12
int x = 1;while (x != 12){ cout << x << endl;
x = x + 2;}How to fix it?
While loopsWhat's wrong with this?
int x = 10; while ( x > 0 ); { cout << x << endl; x--; }
While-loop and for-loop
int x = 1;
while (x < 12)
{
cout<<x<<endl;
x = x + 2;
}
The for loopfor (initialization; expression; increment){
//statements here}
Example: flowchart
int x = 1;
while (x < 12)
{
cout<<x<<endl;
x = x + 2;
}
int x = 1;
while (x < 12)
{
cout<<x<<endl;
x = x + 2;
}
for (x=1; x<12; x=x+2)
{
cout<<x<<endl;
}
int i ;for( i=0; i<10; ++i ){
cout << i << " ";}
int i;for( i=0; i<10; ++i ){
cout << i << " ";}
int i;for (i=0; i<10; i++){
cout <<i << " ";}
int x, n=100;for (x=0; x<n; x++){
x=x+1;}cout<<"x after end of loop is "<<x<<endl;
int x, n=100;for (x=0; x<n; x++){
x=x+1;}cout<<"x after end of loop is "<<x<<endl;
x is the smallest even number >= n
SELF TEST
int x, n=100;
for (x=0; x<n; x++){
cout<<x<<endl;
x=x+1;
}cout<<"x after end of loop is "<<x<<endl;
SELF TEST
int x, n=100;
for (x=0; x<n; x++){
x=x+1;
cout<<x<<endl;
}cout<<"x after end of loop is "<<x<<endl;
The For Loop
int i ;for( i=23; i>=30; ++i ){
cout << i << " ";}
for (i=13; i>=10; --i){
cout <<i <<" ";}
The For Loop
What is wrong here?int i, j, k ;for( i=0; i<10; i-- ){
cout<<i;}
for (i=0; i<10; ){
j=i+30;k=j+30;
}
Fibonacci numbers
F1=1
F2=2
Fn=Fn-1 + Fn-2
1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 10946 17711 28657 …
Related Documents
