Computer Science Canada length() and substr() Are Messed Up... |
| Author: | HRI [ Wed May 05, 2010 7:22 pm ] |
| Post subject: | length() and substr() Are Messed Up... |
For class I have to make a program that given a number between 1 and 1000, outputs that many 'moo' numbers which satisfy 2 conditions: 1. It is even. 2. It is a palindrome. Here's my code, although I've changed it quite a bit to try to make it work. I've also never converted ints to strings before so I'm guessing that's where the problem is. I tried both sstream and itoa. Also, please mention if that break statement won't exit the for loop, as that was my intention. #include <iostream> using std::cout; //cout is like printf using std::cin; //cin is like scan or whatever stdio uses using std::endl; //new line #include <string> using std::string; #include <sstream> #include <cmath> //I would just put 'using namespace std;', but we're not allowed. int main() { bool palindrome = false; //initialize the palindrome check to false. int i = 1, n; //i is for the current number being checked and n is for how many numbers in total. cout << "Enter number of moo numbers: "; cin >> n; for (i = 1; i <= n; i++) { if (i % 2 == 0) //check if it's even. { std::stringstream ss; ss << i; //convert number to string...*** int length = i.length(); //should work, instead says length is not a type. for (int count = 1; count <= ceil (length / 2); count++) //This loop is to compare the first/second etc. with the last/second last etc. and see if they're the same. { string first = i.substr (count - 1, 1); string second = i.substr (length - count, 1); if (first == second) palindrome = true; else break; } } if (palindrome == true) cout << i << endl; palindrome = false; i++; } system ("pause"); //for use in devcpp to pause the window so it won't close before you can read the output. return 0; } |
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| Author: | Tony [ Wed May 05, 2010 7:33 pm ] |
| Post subject: | Re: length() and substr() Are Messed Up... |
HRI @ Wed May 05, 2010 7:22 pm wrote: ... int i = 1, n; //i is for the current number being checked and n is for how many numbers in total. ... int length = i.length(); //should work, instead says length is not a type. "i" is not an object, and thus has no methods. edit: what does length() of an integer even mean? |
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| Author: | HRI [ Wed May 05, 2010 7:38 pm ] |
| Post subject: | Re: length() and substr() Are Messed Up... |
I tried to convert i to a string, so that it would be more like "22" rather than 22, for example. Then you can call those functions using <stringname>.length/substr. Also, I'm unaware of how to enclose my code in one of those fancy boxes. May someone enlighten me? |
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| Author: | Tony [ Wed May 05, 2010 7:46 pm ] |
| Post subject: | RE:length() and substr() Are Messed Up... |
C++ is a statically typed language -- you declare what type a variable "i" is (int), and it stays an int (strictly speaking, the program allocates enough memory for an int, and not enough for a larger String). "i" can't become a String. Use [ syntax="cpp" ] [ /syntax ] tags (sans spaces) to format code blocks |
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| Author: | HRI [ Wed May 05, 2010 7:52 pm ] |
| Post subject: | Re: length() and substr() Are Messed Up... |
Thanks for the help, but is there no way to accomplish this then? Thanks for the code block statements too. |
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| Author: | OneOffDriveByPoster [ Thu May 06, 2010 10:44 pm ] |
| Post subject: | Re: length() and substr() Are Messed Up... |
HRI @ Wed May 05, 2010 7:52 pm wrote: Thanks for the help, but is there no way to accomplish this then?
It just means that i is always going to be an int. It does not mean that you will not be able to produce a string with a representation of the value of i. Look at a reference for the basic_stringstream template class to see how you get a string out of a stringstream. |
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