9th grade CS. Dirrections and opinions

**MrSpyrydus** · 01-26-2012

Hello guys, I'm new on this forum. I'm Alex, 9th grade and i am 16 years old. I started to learn computer science (informatics if directely translated from my language) this year and i love it. I am one of the best students in my CS class and i would love to go to the CS olympiad this year but my teacher told me that it's no hope. They ask for minimum-intermediate knowledge about CPP and we are learning repetitive structures at class. I have to learn cpp in 2 months and i will focus on that but i dont know where to start. CS is the only subject that i enjoy studying but i am really really confused. What do you think? Shoul i focus all my time on studying CS for the next 2 months? or should i just take it easy and wait for 10th grade? Thank you for taking time to read all my grumble and excuse my bad english(i'm romanian)

**Elkvis** · 01-26-2012

I suggest that you take your time and learn as much as you can. two months is not nearly enough time to learn C++ in any meaningful way. I've been using C++ every day for my job for the last 4 years, and I'm still learning. You'd be better off waiting the extra year. you can get a good understanding of C++ in a year, and you would have a really good chance of doing well at the olympiad.

**manasij7479** · 01-26-2012

I was in a similar situation about 3 years ago at 15.(Though the Olympiad in my case was much easier and I got a single digit national rank).
Though learning C++ is not a task for 2 months, you can easily learn the subset you are expected to know, if you get a good book and do not stumble on logical thinking (that is where most fail during learning programming).
Good luck.

**MrSpyrydus** · 01-26-2012

i need a little bit of help. i want to know what i have to use to solve this problem. i dont want you to solve it just give me a hint. "a random number of characters and numbers will be read from the keyboard. what is the smalles number that can be formed from the numbers? write the characters in the same order but all of them have to be uppercase" i dont know how to make the characters uppcase and how to make the repetitive structure work for an undetermined number of integers. i hope it is understandable and you can help me. thank you

**Elysia** · 01-26-2012

std::toupper will convert any character to its upper-case counterpart.
Regarding flow structures, there are while loops, for loops and do while loops. Study them and make a flow chart. It isn't harder than that, really.

**seanJ** · 01-26-2012

it helps a lot if you take a problem and break it into smaller and smaller problems.

"take a random number of characters and numbers from the keyboard, find the smallest number and print all characters excluding numbers in upper case in the same order"

"take a random number of characters from the keyboard"
"find the smallest number"
"print the smallest number"
"exclude all non-letters"
"capitalize all letters"
"print all letters"

if any single part seems like it's just too much then only deal with part of that part.

for the input try using the string data type in C++

**Elkvis** · 01-26-2012

what is the smalles number that can be formed from the numbers?

note that it doesn't say "what is the smalles number that can be formed from all the numbers?"

this should give you a hint, if in fact it is taken verbatim from the description of the problem.

**MrSpyrydus** · 01-27-2012

the problem is translated from romanian but at the example for the number part they say "if the given numbers are 3, 3, 4, 5, 1 then the smalles number that can be formed is 1345" so i guess the number is formed using every number only once. so if the number 5 appears 3 times tou use it only once. once again sorry for my bad english skills

**Elkvis** · 01-27-2012

in that case, it's just a matter of sorting from lowest to highest and removing duplicates. there are standard <algorithm> functions for both operations.

**MrSpyrydus** · 01-27-2012

can you guys explain me exactly what does get.int() does? and can you tell me if i can assign a number or char to a void data and then check which tipe is assigned? thank you alot

PS: i would love some explanations on the array thing. i dont know what this code does but i would like to show me the value from the possition input from the keyboard. but for x=3 for example i get the number 153...can you explain me exactly how it works? thank you alot

Code:

#include <iostream>


using namespace std;


int main()
{
    int array[5];
    int x;
    cin>>x;
    cout<<array[x];
    cin.ignore();
    cin.get();
}

**Elysia** · 01-28-2012

The values contained inside variables is undefined unless initialized or are global.

**MrSpyrydus** · 01-28-2012

i still dont get it

**oogabooga** · 01-28-2012

Local variables are created on the stack and are uninitialized unless you do so yourself. So they will contain whatever garbage happens to be there. Global variables are automatically zeroed if they are not explicitly initialized.

**MrSpyrydus** · 01-28-2012

i kinda got that. and for the other question: how can you determine what is input from the keyboard and assign it to a speciffic array?

**Elysia** · 01-28-2012

What do you mean?

int array[n]; // Where n is a constant
std::cin >> array[x]; // Where x is another constant, and x = [0, n - 1]

This is enough to read from the keyboard to an array.

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