C++ Help

[crazyfool]

hey guys,
I have just started my latest piece of coursework but i am having problems with a couple of things. Firstly i have used this method:
string something
ifstream file ("sometext.txt");
file >> something
This reads a text file into the string and then i have some code which seperates each word into a vector. This all works fine but... I need to be able to know when a then end of a line within the text being stored in a vector is reached. I know if i had used the getline method this would have been possible but before i go rewriting my code i wanted to know if there was another way.
Secondly each vector stores a word and another vector stores numbers... how can i sort the vectors alphabetically and the other in numerically... any advice would be appreciated

[aidanjt]

Use a heap of strings, what's the purpose of using vectors for each word? Classic case of over-engineering trivial problems.

[crazyfool]

lol nah i have to use vectors because i dont know the amount of words i'll need to store... plus it says i have to on the coursework lol

[aidanjt]

I see, that figures. Does the coursework specify atomising the strings into words?.. Or just using vectors for 'storage'?..
I'd avoid that mess as much as possible unless I were to structure it. Otherwise the vector items become meaningless chunks of bytes. And yes, getline() would be easier, but you can just as easily look for EOL markers yourself, they're no different than spaces or any other character as far as string is concerned. As long as you remember to keep them in your vector entries you shouldn't have much of a problem.

[crazyfool]

ok i fixed that problem... now i have a new one :<... if i have a string x how can i look through the string to see if it contains a certain word or number

[aidanjt]

Would string::find() do?

[Fraz]

Secondly each vector stores a word and another vector stores numbers... how can i sort the vectors alphabetically and the other in numerically... any advice would be appreciated

The STL provides several algorithms to sort elements of a range. Make sure you're not using the incorrect data structures in the first place though and are sorting to correct this problem!

for instance there is:

void std::sort(RandomAccessIterator begin, RandomAccessIterator end).

This will sort by default according to the "<" operator, which should do what you want in both cases.

You get the "begin" and "end" iterators from your vectors like this:

myVector.begin()
myVector.end()


Do they actually teach you any C++ before they send you off with this coursework?!

I suggest you buy this book:

http://www.amazon.co.uk/C-Standard-L.../dp/0201379260

[Fraz]

Here is some example code.

#include <vector>
#include <string>
#include <iostream>

using namespace std;

int main()
{
  vector<string> myStringVec;
  myStringVec.push_back("ba");
  myStringVec.push_back("ab");
  sort(myStringVec.begin(), myStringVec.end());
  cout << myStringVec.at(0) << myStringVec.at(1) << endl;  // prints "abba" rather than "baab".
  return 0;
}

[crazyfool]

EDIT: Ok can someone tell me wot is wrong with this...
string xx = "1, 2, 3, "
string x = "4"
if xx.find(x) = false then
do something
else
do something else
it doesn't seem to find a match in the string if there is one e.g. x = 1 and if there isn't it doesn't seem to return false...HELP!!!!!!

[Fraz]

EDIT: Ok can someone tell me wot is wrong with this...
string xx = "1, 2, 3, "
string x = "4"
if xx.find(x) = false then
do something
else
do something else
it doesn't seem to find a match in the string if there is one e.g. x = 1 and if there isn't it doesn't seem to return false...HELP!!!!!!

You have at least two problems here:

Firstly you are using a single = sign when trying to do an "equals to" comparison (I doubt this would compile anyway, so maybe you aren't actually making this mistake).

Secondly, the find function returns string::npos if it fails to find the substring you are searching for (this is probably (2^32)-1 or some such number). If it does find the substring you are looking for then it returns the index of the first character of the substring in the string in which you are performing the search.

So... if you set x = 1, this is at position 0 of xx. Thus your logic will claim it hasn't found this string even when it has (the find method will be returning zero which also equates to false). In any other circumstance your code will be claiming it has found the string regardless of what actually has happened.

[crazyfool]

cheerz m8 got that sorted now... now i have another seperate problem

int i = 0;
i = i + 1;
char c = i;
string s = c;

this code is used to print out a series of numbers however after it gets to number eight it starts print symbols and letters... i only used this code to convert int to a string but i cant use itoa because it is not allowed... anyone know how to fix this

[Fraz]

cheerz m8 got that sorted now... now i have another seperate problem

this code is used to print out a series of numbers however after it gets to number eight it starts print symbols and letters... i only used this code to convert int to a string but i cant use itoa because it is not allowed... anyone know how to fix this

If you are using a stream insertion operator (i.e. <<), it should take care of this for you anyway:

int myInt = 58; 
cout << myInt << endl;

will print 58 to the screen.

If you need to convert an integer for some other purpose, you can use ostringstreams:

  int myInt = 58;
  ostringstream oss;
  oss << myInt;
  string myIntAsString = oss.str();

Not the most CPU-efficient way possible, mind.

By the way, what you were doing is the most god-awful hack imaginable

[crazyfool]

dude you are awesome lol... last question i promise... is there a way for me to remove certain characters from string... e.g.
string str = "hexus-forums"
how can i remove the "-" to leave it as "hexusforums"