I'm writing a program to parse some data saved as text files. What I am trying to do is find the location of every needle in a haystack. I already can read the file in and determine the number of occurrences, but I am looking to find the index also.
string str,sub; // str is string to search, sub is the substring to search for
vector<size_t> positions; // holds all the positions that sub occurs within str
size_t pos = str.find(sub, 0);
while(pos != string::npos)
{
positions.push_back(pos);
pos = str.find(sub,pos+1);
}
Edit I misread your post, you said substring, and I assumed you meant you were searching a string. This will still work if you read the file into a string.