Thread: counting strings

Code:

#include <iostream>
#include <string>
#include <fstream>
#include <array>

#define MYFILE "/Users/peterjocham/Desktop/textfile.txt"

using namespace std;

int main()
{
    ifstream infile(MYFILE,ios::in);
    
    string s;
    int count=0;
    
    getline(infile, s);
    
    for (int i=0; i<sizeof(s);i++)
    {
        if(s[i]=='a'&&'n'&&'d')
        {
            count++;
        }
    }
    
    cout<<"and appeared: "<<count<<" times"<<endl;
    
    
    return 0;
}

I am trying to count how many time the word 'and' occurs but I am getting wrong numbers.

Code:

        if(s[i]=='a'&&'n'&&'d')

that won't do what you want, it will be true for each 'a'
try

Code:

 if(s[i]=='a' && s[i+1]='n' && s[i+2]=='d')

Beware of out of bounds accesss

Kurt

Yes, you could put the getline call as the condition for a while loop.
The other mistake is that sizeof() wont return the length of the string
Kurt

Code:

 for (int i=0; i<s.size();i++)
        {
            if(s[i]=='a' && s[i+1]=='n' && s[i+2]=='d')
            {
                count++;
            }
        }

Got it working... The file had a '/n' and therefore it stopped read it. How would I ignore this? Lets say I want to search a whole book or paragraph for certain words, count them etc.

Originally Posted by jocdrew21

Lets say I want to search a whole book or paragraph for certain words, count them etc.

as I said before try

Code:

while ( getline(infile, s) ) {
    ... // your for loop
}

And you are still accessing the string out of bounds

Kurt

You should use size()-2 in that for loop. So long as there's a newline at the end it won't crash, because if s[i] == '\n' then s[i] != 'a', so the other two conditions aren't evaluated. At the end of a file though there might not be a newline.

getline() will stop when it reads a newline, so you need to put another loop around it all. You can put getline in a while loop like so:

while(getline(infile, s))
{

The while loop will terminate when you get to the end of the file. By scary C++ black magic which I've tried and failed to understand.

I got it to work. Now I am messing around with capitalizing "and" to "AND" and outputting it back to the txt file.

Thank you for the help...

You could have also used s.find("and") -- string::find - C++ Reference

Good luck with that! It'd definitely be easiest to write a new file copying over each line from the old one, with the string modified when there are "and"s. It should be possible to do it without doing that by tracking and manipulating the get and put pointers. I've never wanted to avoid a file copy and replace badly enough to try it!

Hi, in this case the easy way is to use the operator >>, It returns the istream object that evaluates to false/true if you use it like a boolean.

Code:

...
while(infile >> s){
        count += s == "and";
}
...

Regards.

Code:

#include <iostream>
#include <string>
#include <fstream>

#define MYFILE "/Users/peterjocham/Desktop/textfile.txt"

using namespace std;

int main()
{
    ofstream outfile(MYFILE,ios::app);
    
    ifstream infile(MYFILE,ios::in);
    
    string s;
    int count=0;
    
    while(infile >> s)
    {
            count += s == "and";
    }
    
    cout<<"and appeared: "<<count<<" times"<<endl;
    cout<<s;
    
    
    return 0;
}

Tried it your way and it is not working... I am getting 9 and's and I have 16 in the file.

Ok, I think you are looking for the string "and" matching over the text, and not the words "and" that there are in, that's different. So try to use string::find.

Code:

while(infile >> s)
    {
       if(s.find("and")==false)
       {
           count++;
       }
        
    }

This is working but it is only reading the first paragraph.

This code read the whole page and searched for "and" :

Code:

while(getline(infile, s))
    {
 
        for (int i=0; i<s.size();i++)
        {
            if(s[i]=='a' && s[i+1]=='n' && s[i+2]=='d')
            {
                s[i]='A';
                s[i+1]='N';
                s[i+2]='D';
                count++;
            }
        }
         
    }

However I was accessing the string out of bounds.

You need to read the documentation for the string.find() function. It doesn't return a bool, it returns a size_t, and it doesn't return zero if it doesn't find the string it returns string::npos. Also when it finds the string it returns the position in the string where the found string starts.

If you're using the extraction operator instead of getline() you don't actually need the string.find() function just use the comparison operator.

Code:

if(s == "and")
 ...

Jim