std::vector iterator or index access speed question
- by Simone Margaritelli
Just a stupid question .
I have a
std::vector<SomeClass *> v;
in my code and i need to access its elements very often in the program, looping them forward and backward .
Which is the fastest access type between those two ?
Iterator access
std::vector<SomeClass *> v;
std::vector<SomeClass *>::iterator i;
std::vector<SomeClass *>::reverse_iterator j;
// i loops forward, j loops backward
for( i = v.begin(), j = v.rbegin(); i != v.end() && j != v.rend(); i++, j++ ){
// some operations on v items
}
Subscript access (by index)
std::vector<SomeClass *> v;
unsigned int i, j, size = v.size();
// i loops forward, j loops backward
for( i = 0, j = size - 1; i < size && j >= 0; i++, j-- ){
// some operations on v items
}
And, does const_iterator offer a faster way to access vector elements in case i do not have to modify them?
Thank you in advantage.
