substrings and loops, messing up real bad!

Code:

#include <iostream>
using namespace std;

int main ()
    {
    string wd[50];
    cout<<"Trivia will begin"<<"\n"<<"\n";
    wd[1] = "hello";
    wd[2] = "need";
    wd[3] = "help";
    wd[4] = "yell";
    wd[5] = "box";
    string subs[50];
    int low_index = 1;
    int high_index = 5;
    int lsub_index = low_index;
    int hsub_index = high_index;
    bool subs_has_set[50];
    int players_points;
    for (int t = 0; t < 51; t++)
        {
        subs_has_set[t] = false;
        }
    int x; int i;
    bool cont = true;
    string players_word;
    string scrambledword;
    //makes a random number, to select the word we will use
    srand((unsigned)time(0));   
    x = 1; //(rand()%high_index)+low_index;
    //gets the length of the string for the while loop
    string::size_type word_length = wd[x].length();
    
    cout<<"0,1 = "<<wd[x].substr(0,1)<<"\n";
    //begins to set subs[] to each letter of wd
    cout<<"wd[x] == "<<wd[x]<<","<<"\n"<<"Length = "<<word_length<<"\n"<<"\n";
    while (low_index-1 < word_length)
        {
        subs[low_index] = wd[x].substr(low_index-1, low_index);
        cout<<"subs["<<low_index<<"] == "<<subs[low_index]<<"\n"<<"\n";
        low_index++;
        }
    //loops so all characters are used and not overlap
    while (cont == true)
        {
        i = (rand()%word_length)+1;
        if (subs_has_set[i] == false)
            {
            scrambledword = scrambledword + subs[i]; 
            subs_has_set[i] == true;   
            cout<<"subs[i], "<<subs[i];       
            }
        string::size_type new_word_length = scrambledword.length();
        if (new_word_length == word_length)
            {
            cont == false; 
            } 
        cin.get();
        }
    cout<<"Word to unscramble is "<<scrambledword<<", Good luck "<<"\n";
    getline(cin, players_word);
    if (players_word == wd[x])
        {
        players_points = players_points + 1;
        cout<<"Correct, +1 Point";
        }
    cin.get();
    }

the red part, is suppost to loop through each letter of the word, and add it to subs[low_index]but when I display it, it ends up

- updated with latest code

please help!


I did this

subs[low_index] = wd[x].substr(low_index-1, low_index);

and got

subs [1] = h
subs [2] = el
subs [3] = llo
subs [4] = lo
subs [5] = o

which is closer

Code:

subs[low_index] = wd[x].substr(low_index, low_index);

Low to low? That'll give you a string with a character in it, right? Or perhaps nothing at all?

Low to low? That'll give you a string with a character in it, right?

No...

Oh, nevermind.

so in c++ substr "hello" 1,1 = (nothing)

?

weird i'll try

low_index, low_index+1

its now

subs [1] = el
subs [2] = llo
subs [3] = lo
subs [4] = o
subs [5] =

hmm?

I did this

subs[low_index] = wd[x].substr(low_index-1, low_index);

and got

subs [1] = h
subs [2] = el
subs [3] = llo
subs [4] = lo
subs [5] = o

which is closer

Code:

string subs[50];
string wd[50];

wd[4] = "hello";
string::size_type word_length = wd[4].length();

int low_index = 0;
while (low_index < word_length)
{
    subs[low_index] = wd[4][low_index];  
    cout<<"subs["<<low_index<<"] == "<<subs[low_index]<<"\n"<<"\n";
    
	low_index++;
}

If you have a string like this:

string str = "hello";

You can access any character using the syntax str[2], which in this case would be the 3rd character(because arrays start at index 0).

In the example above wd[4] is a string, so its characters can be accessed using the same syntax: wd[4][2], where wd[4] is the name of the string and [2] accesses the 3rd character.

OMG, thanks alot

so in c++ substr "hello" 1,1 = (nothing)

You should really get a book and/or find a website to look up the definitions of C/C++ functions. You can't just use a function like substr() and not know what arguments it expects and how substr() uses those arguments. The first number is the start position in the string, and the second number is the length. Therefore, in the special case when you use 1 for both arguments, then substr(1, 1) returns 1 character. However, more generally if you write substr(3,3), then substr() returns 3 characters(if there are 3 characters in the string past index position 3).

confusing, I do have a index thing manual open, yes I'll get a book, (no chances to go to library yet! i cant drive lol!

hmm
confusing,

Let's try it another way. If you write:

string myStr = "hello world";
string result = myStr.substr(2,2);

you are asking the substr() function to copy some characters from myStr into result. The first argument says to start copying at index position 2 in myStr, and that is the first 'l'.

The second argument says to copy 2 characters in total. So, result will contain 'll'.

ohhh, I see

its different from what I have learnt (other languages)

so

string m = "hello"
string res = m.substr(2,1)
being 'l' and only 1 character....

so

I see! thanks

> for (int t = 0; t < 51; t++)
This should be
for (int t = 0; t < 50; t++)

> while (cont == true)
You shouldn't really compare boolean variables for true / false, since they already are true / false
while ( cont )
should suffice.

> cont == false;
Now this should have been
cont = false;

A good compiler would have warned you about a useless comparison, did yours?

no, my compiler is dev - C++

lol

In the project settings, you can add additional flags

Say
-W -Wall -ansi -pedantic -O2