Finding words in sentences [closed] - c++

Question

Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 8 years ago.
Improve this question
I have a programming assignment I cannot finish. This one part is killing me.
Accept some text from the user. Accept the string that needs to be searched. Your program is supposed to print the number of occurrences of the string found within the text, and the position at which the pattern was found. Look at the following sample output:
Sample Output:
Enter text: “Call me Ishmael. Some years ago - never mind how long precisely - having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world. It is a way I have of driving off the spleen, and regulating the circulation”
String to search – “Some years ago”
Number of occurrences – 1
Position Found – 18
This is my function:
void getText()
{
string itext, word;
int position;
bool done = false;
cout << "Enter some text" << endl;
cin >> itext;
cout << "Enter the word or phrase to wish to find" << endl;
cin >> word;
char text[itext.length()];
char search[word.length()];
for(int i = 0; i < itext.length(); i++)
{
for(int j = 0; j < word.length(); j++)
{
if(text[i] == search[j])
{
position = i;
cout << position;
}
}
}
}

Answer 1

This might get you started: (pseudo code from the Knuth-Morris-Pratt algorithm)
algorithm kmp_search:
input:
an array of characters, S (the text to be searched)
an array of characters, W (the word sought)
output:
an integer (the zero-based position in S at which W is found)
define variables:
an integer, m ← 0 (the beginning of the current match in S)
an integer, i ← 0 (the position of the current character in W)
an array of integers, T (the table, computed elsewhere)
while m + i < length(S) do
if W[i] = S[m + i] then
if i = length(W) - 1 then
return m
let i ← i + 1
else
if T[i] > -1 then
let m ← m + i - T[i], i ← T[i]
else
let i ← 0, m ← m + 1
(if we reach here, we have searched all of S unsuccessfully)
return the length of S
http://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm
EDIT:Simpler and using c++ std library :
#include <string>
#include <vector>
int main ()
{
std::string str ("There are two needles in this haystack with needles.");
std::string str2 ("needle");
// different member versions of find in the same order as above:
std::size_t found = 0;
int matches = 0;
std::vector<size_t> positions;
while( found = str.find(str2) != std::string::npos) {
matches++;
positions.push_back(found);
}
}

Answer 2

You can make your live much easier if you will use std::string in this task instead of char[]. All you have to do is to load your text into a std::string and then use its find method as described here:
http://www.cplusplus.com/reference/string/string/find/
By the way, I am not sure that these lines can work as you can create not dynamic array only with a constant expression length
char text[itext.length()];
char search[word.length()];