You need to make use of the begin and end method of the vector class, which return the iterator referring to the first and the last element respectively. using namespace std; vector<string> myvector; // a vector of stings. // push some strings in the vector. myvector.push_back(“a”); myvector.push_back(“b”); myvector.push_back(“c”); myvector.push_back(“d”); vector<string>::iterator it; // declare an iterator … Read more
I need to iterate by characters scanning for it. The .chars() method returns an iterator over characters in a string. e.g. for c in my_str.chars() { // do something with `c` } for (i, c) in my_str.chars().enumerate() { // do something with character `c` and index `i` } If you are interested in the byte … Read more
any won’t go beyond the first element if it’s True. In case the iterator yields something false-ish you can write any(True for _ in iterator).
The grouper() recipe from the itertools documentation’s recipes comes close to what you want: def grouper(n, iterable, fillvalue=None): “grouper(3, ‘ABCDEFG’, ‘x’) –> ABC DEF Gxx” args = [iter(iterable)] * n return izip_longest(fillvalue=fillvalue, *args) It will fill up the last chunk with a fill value, though. A less general solution that only works on sequences but … Read more
>> @budget = [ 100, 150, 25, 105 ] => [100, 150, 25, 105] >> @actual = [ 120, 100, 50, 100 ] => [120, 100, 50, 100] >> @budget.zip @actual => [[100, 120], [150, 100], [25, 50], [105, 100]] >> @budget.zip(@actual).each do |budget, actual| ?> puts budget >> puts actual >> end 100 120 … Read more
Looking at the Java API Specification for the Iterator interface, there is an explanation of the differences between Enumeration: Iterators differ from enumerations in two ways: Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics. Method names have been improved. The bottom line is, both Enumeration and … Read more
Here are three possibilities: foo = “”” this is a multi-line string. “”” def f1(foo=foo): return iter(foo.splitlines()) def f2(foo=foo): retval=”” for char in foo: retval += char if not char == ‘\n’ else ” if char == ‘\n’: yield retval retval=”” if retval: yield retval def f3(foo=foo): prevnl = -1 while True: nextnl = foo.find(‘\n’, … Read more
C++11 This has been fixed in C++11 (or erase has been improved/made consistent across all container types). The erase method now returns the next iterator. auto pm_it = port_map.begin(); while(pm_it != port_map.end()) { if (pm_it->second == delete_this_id) { pm_it = port_map.erase(pm_it); } else { ++pm_it; } } C++03 Erasing elements in a map does not … Read more
Quick answer: Doing list() around a generator expression is (almost) exactly equivalent to having [] brackets around it. So yeah, you can do >>> list((x for x in string.letters if x in (y for y in “BigMan on campus”))) But you can just as well do >>> [x for x in string.letters if x in … Read more
You still need to check if (items != null) otherwise you will get NullReferenceException. However you can do something like this: List<string> items = null; foreach (var item in items ?? new List<string>()) { item.Dump(); } but you might check performance of it. So I still prefer having if (items != null) first. Based on … Read more