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How to create substrings from a sentence string C++

Posted on 2008-10-23
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Ok this is what I am trying to do, in C++ language, I can create a string, what I want to go is take a sentence say "Here is a sentence that I want the program to use." How do I get the program to break each word into a substring so I can count the vowels in a loop, and then know to stop the loop when it gets to the .?
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Question by:putyoursoxon
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10 Comments
 
LVL 39

Expert Comment

by:itsmeandnobodyelse
ID: 22795510
You could use STL for example

#include <string>
using namespace std;

    ....

    string s = "Here is a sentence that I want the program to use.";
    s += ' ';   // add a space for easier parsing
    int pos1 = 0;
    int pos2 = 0;
    while ((pos2 = s.find_first_of(" ,.;/|", pos1)) != string::npos)
    {
         if (pos2 > pos1)
         {
              string sub = s.substr(pos1+1, pos2-pos1+1);
              // here you could store the found token to a vector, e.g by v.push_back(sub);
              if (s[pos2] == '.')   // ok we found the .
              {
               }
         }
    }
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LVL 39

Expert Comment

by:itsmeandnobodyelse
ID: 22795521
I forgot to add

    pos1 = pos2 +1;

at end of loop.
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Author Comment

by:putyoursoxon
ID: 22802736
I tried this, but this will not work correctly it includes the space and the first letter of the next word in the current word
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LVL 39

Expert Comment

by:itsmeandnobodyelse
ID: 22803001
>>>> it includes the space and the first letter of the next word in the current word

Sorry, it should be

   pos2-pos1-1
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Author Comment

by:putyoursoxon
ID: 22803062
Ok, let me write this into what I have so far and see how it goes, thanks
0
 

Author Comment

by:putyoursoxon
ID: 22804502
this also doesnt work does the same thing except it does it with the first word in a infinite loop
0
 
LVL 39

Accepted Solution

by:
itsmeandnobodyelse earned 1500 total points
ID: 22806592
Take that
#include <string>
#include <iostream>
#include <iomanip>
#include <vector>
using namespace std;
 
int tokenize(const string & sin, vector<string> & tokens, vector<char> & separators)
{
    string s = sin;
    s += char(0);    // add a 0 char for getting end-of-string parsing
    string seps = " ,.;/|";
    seps += char(0);    
    int pos1 = 0;
    int pos2 = 0;
    while ((pos2 = s.find_first_of(seps, pos1)) != string::npos) 
    {
         if (pos2 > pos1)
         {
              string sub = s.substr(pos1, pos2-pos1);
              tokens.push_back(sub);
              separators.push_back(s[pos2]);
        }
        pos1 = pos2+1;   // don't forget that or you'll get an infinite loop
    }
    return tokens.size();
}
 
int main()
{
       int i; 
       string s = "Here is a sentence that I want the program to use.";
       vector<string> substrings;
       vector<char>   separators;
 
       int n = tokenize(s, substrings, separators);
       for (i = 0; i < n; ++i)
       {
            char c = separators[i];
            cout << setw(3) << right << i+1 << " " << left << setw(20) <<  substrings[i] 
                 << " separated by " << int(separators[i]) << " " << separators[i] << endl;
       }
       cin >> i;
       return 0;
}

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Author Closing Comment

by:putyoursoxon
ID: 31509452
im going to try a streamstring instead
0
 
LVL 39

Expert Comment

by:itsmeandnobodyelse
ID: 22807673
>>>> im going to try a streamstring instead
The problem with streaming is that you could go for one delimiter only. In your case it is a space. But then, the fulstop at end must be parsed separately.
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Author Comment

by:putyoursoxon
ID: 22808132
With streamstring can I use a terminating character like . To count as the end of a sentence?
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