Program throwing exception - c++

Question

I am writing a program that allows the user to enter a sentence which then gets stored in a string and then the program will remove any full stops in the sentence and then create a list of each individual word in the string before outputting that list to the console.
the program is working perfectly as long as there is only 1 full stop in the sentence but if there are any more than that it throws this exception:
Unhandled exception at at 0x7696B727 in Project6.exe: Microsoft C++ exception: std::out_of_range at memory location 0x0022F8B8.
and then if I continue to run it it throws:
Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.
any suggestions? (and before anyone asks, i know you usually only have 1 full stop in a sentence but i need to do it with more than 1 as part of testing.
here is the code:
#include <iostream>
#include <string>
using namespace std
string sSentence; // sets up a string variable called sSentence
int i = 0;
void RemoveFullStop()
{
while(sSentence.find (".") != string::npos) // the program runs this loop until it cannot find any more full stops in the string
{
i = sSentence.find("." , i); // find the next full stop in the string and get the character count of the space and place it in the variable i
sSentence.replace(i,1,""); // remove the full stop
}
}
void ListWords()
{
while(sSentence.find (" ") != string::npos) // the program runs this loop until it cannot find any more spaces in the string
{
i = sSentence.find(" " , i); // find the next space in the string and get the character count of the space and place it in the variable i
// cout << i << endl; // output the contents of iWordSpace to the console (used for debugging - no longer used)
sSentence.replace(i,1,"\n");
// cout << sSentence << endl; // output the contents of iWordSpace to the console (used for debugging - no longer used)
}
}
int main()
{
getline(cin, sSentence); // get user input and store it in sSentence (using the getline function so the .find operation works correctly)
RemoveFullStop(); // calls the RemoveFullStop void function that removes all full stops from the string
ListWords(); // calls the ListWords void function that splits the string into a list of words
cout << endl; // formatting line
cout << "The words that were in the sentence were:" << endl;
cout << endl; // formatting line
cout << sSentence << endl;
cout << endl; // formatting line
system("pause");
return 0;
}

Answer 1

The problem is that you keep re-using i, in both RemoveFullStop and ListWords.
i only ever increases, and so eventually it can get past the end of the string.
You really shouldn't need a global i variable at all, to do this task.

Answer 2

The reason this happens is that when sSentence.find(" " , i) in ListWords runs, i's value is not 0 because it was already defined in RemoveFullStop(). To fix this, first remove int i = 0;, then add it to RemoveFullStop() and ListWords()
Also, while this is just a style thing and won't effect your codes ability to run, I wouldn't call this variable i as i,j,k usually imply counters. Call this variable something more appropriately descriptive.
Here is the relevant code as it should be.
using namespace std
string sSentence;
void RemoveFullStop()
{
int charPlace = 0;
while(sSentence.find (".") != string::npos)
{
charPlace = sSentence.find("." , charPlace);
sSentence.replace(charPlace,1,"");
}
}
void ListWords()
{
int charPlace = 0;
while(sSentence.find (" ") != string::npos)
{
charPlace = sSentence.find(" " , charPlace);
sSentence.replace(charPlace,1,"\n");
}
}