View Full Version : [SOLVED] Problem With Vector Erase C++

March 14th, 2010, 02:19 AM
Ey guys, I have a function that takes in two positions and a vector and removes those positions from the vector, like so:

void removeFromTo(vector<string>& vect, long begPos, long endPos){
cout << "beg, end: " << begPos << ", " << endPos << endl;
vect.erase(vect.begin()+begPos, vect.begin()+endPos);

But it fails to remove the first element from the vector, here is some program output:

//elements in the vector:
/ * * / $#
0 1 2 3 4 5 6
//beg and end are printed from within the function
beg, end: 0, 4
/ $#

So I still have that first '/'. Here is another example:

e / * * / $#
0 1 2 3 4 5 6 7
beg, end: 1, 5
e / $#

Yeah, so I don't know what I should do, any help appreciated and thank you.

Another odd thing, I changed the call of the function to:

removeFromTo(actualLine, charTypeAstrkBegCmnt(line, tokensVect[lineNum-1])-1, \
charTypeAstrkEndCmnt(line, tokensVect[lineNum-1])+1);


removeFromTo(actualLine, charTypeAstrkBegCmnt(line, tokensVect[lineNum-1]), \
charTypeAstrkEndCmnt(line, tokensVect[lineNum-1])+1);

and this is my output:

e / * * / $#
beg, end: 0, 5
/ $#

So it seems like it REALLY wants to keep the '/' for some reason.

March 14th, 2010, 02:38 AM
Sorry, my post was useless.

vector.erase(iterator beg, iterator end) will delete from beg to end INCLUDING beg and NOT INCLUDING end.

In other words, what is being displayed is your second /.

Got that from here: http://www.cplusplus.com/reference/stl/vector/erase/

March 14th, 2010, 02:38 AM
to me your output is working correctly (assuming the three spaces in your data indicate a space token)
the / is not the first but the second in your array

erase (as all other STL algorithms) takes a past-end iterator for its second argument. Its not the last element removed to be removed, it is the element which comes after the last removee!
so erase 0,4 removes: / * space * but not the next /

also a vector is no structure you usually want to call erase on if its not the end of the vector. Random location erases trigger reallocations.
list may be a more appropriate structure.

March 14th, 2010, 02:43 AM
Oh wow, you were right, thanks man. You are probably right about the lists thing but I have my entire code implemented with vectors, if I run into problems, I will consider your advice. Thanks again.