Question

Write a C++ program which will ask the user to enter an integer from 1 to 15 and displays a number pyramid (implement input validation). For example, if the input is 4 the output will be as follows:

1
2 1 2
3 2 1 2 3
4 3 2 1 2 3 4

Answer 1

I can't seem to get the format on how to display the spacing correct, any ideas?

Answer 2

post your code at a site like http://ideone.com so we can take a look at how it works, and work from there to get it right :-D

Answer 3

mk,

Answer 4

http://codepad.org/RA399grb

Answer 5

They also gave me this as a hint:

The user input represents the total number of lines in the pyramid. Each number occupies three spaces. You must use nested loops to implement your program.

(Hint: Each line has three parts)

Answer 6

The hint suggests that you use an outer loop that walks through each line, and one or more inner loops which prints the numbers on each line.

Answer 7

The question is, how do I do that? :P

Answer 8

nested for loops.

You can start by prompting the user to enter a number from 1 to 15. Your outer for loop will work for that number of iterations.

Answer 9

Why is this saying cout is undefined?

http://codepad.org/XBzfcyfd


Line 19: error: iostream: No such file or directory
Line 18: error: iomanip: No such file or directory
Line 3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'namespace'
In function 'main':
Line 6: error: 'cout' undeclared (first use in this function)
Line 6: error: (Each undeclared identifier is reported only once
Line 6: error: for each function it appears in.)
Line 8: error: 'cin' undeclared (first use in this function)
Line 10: error: expected ';' before 'num'
Line 11

Answer 10

you're compiling it in C :-P choose C++ as the language.

Answer 11

Ohhhhh...

Answer 12

So now do you have any ideas on the spacing/number counting part?

Answer 13

To get them spaced correctly, you can have one loop inside the outer loop just printing spaces, and then a second loop (inside the outer loop but after the first loop that just prints spaces) actually print the numbers.

Answer 14

But how would I know how many spaces to print if i dont know the number of numbers they want yet?

Answer 15

You should write your program so that it figures out the number of spaces to print, according to user input from std::cin

Answer 16

Here's my solution to it, but it doesn't scale well to numbers greater than 9 http://ideone.com/fqqg2

Answer 17

wow, your good

Answer 18

If you're not opposed to using C's printf(), then maybe the solution will also scale to larger numbers.

Answer 19

http://ideone.com/HNK78

Answer 20

when the double digits come into play it pushes them over a bit

Answer 21

yeah.

Answer 22

maybe this?
http://ideone.com/jdIMu

Answer 23

Me thinks so

Answer 24

yes yours works right

Answer 25

Mk, just checking, Thanks for the help!

Answer 26

While writing the solution to this, I ended up getting this kind of output: Number Parallelogram! http://ideone.com/sGWpB

Answer 27

lol? I like that one :P

Answer 28

http://ideone.com/loJdi

Answer 29

Oh snap,

Answer 30

Lol, I'm going to print that out and hand it to the professor :P

Answer 31

1 question though, how come you like to use std::cout instead of just
using namespace std;
and then cout

Answer 32

I like writing std:: everywhere. Helps me learn C++.

Answer 33

lol,
are you being serious?

Answer 34

yes

Answer 35

how does that help?

Answer 36

http://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-a-bad-practice-in-c

Answer 37

No need to worry too much about that stuff when you're just learning C++ though :-P

Answer 38

ah

Answer 39

I'm lazy, I'll use cout << "Until its necessary to switch :P " << endl;

Answer 40

Classes are over now! This semester is finished! Now its time to party!