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Chapter 10. Generic Algorithms

##Exercise 10.1 and 10.2 ##Exercise 10.3 and 10.4 ##Exercise 10.5 ##Exercise 10.6 ##Exercise 10.7

Exercise 10.8:

We said that algorithms do not change the size of the containers over which they operate. Why doesn’t the use of back_inserter invalidate this claim?

Cause the back_inserter is a insert iterator, what iterator adaptor that generates an iterator that uses a container operation to add elements to a given container.

the algorithms don't change the size, but the iterator can change it by using the container operation.

##Exercise 10.9

Exercise 10.10:

Why do you think the algorithms don’t change the size of containers?

@Mooophy: The aim of this design is to separate the algorithms and the operation provided by member function.

@pezy: Cause the library algorithms operate on iterators, not containers. Thus, an algorithm cannot (directly) add or remove elements.

##Exercise 10.11 ##Exercise 10.12 ##Exercise 10.13

Exercise 10.14:

Write a lambda that takes two ints and returns their sum.

auto add = [](int lhs, int rhs){return lhs + rhs;};

Exercise 10.15:

Write a lambda that captures an int from its enclosing function and takes an int parameter. The lambda should return the sum of the captured int and the int parameter.

int i = 42;
auto add = [i](int num){return i + num;};

##Exercise 10.16 ##Exercise 10.17 ##Exercise 10.18 and 10.19 ##Exercise 10.20 and 10.21 ##Exercise 10.22

Exercise 10.23:

How many arguments does bind take?

Assuming the function to be bound have n parameters, bind take n + 1 parameters. The additional one is for the function to be bound itself.

##Exercise 10.24 ##Exercise 10.25

Exercise 10.26:

Explain the differences among the three kinds of insert iterators.

  • back_inserter uses push_back.
  • front_inserter uses push_front.
  • insert uses insert

This function takes a second argument, which must be an iterator into the given container. Elements are inserted ahead of the element denoted by the given iterator.

Exercise 10.38:

List the five iterator categories and the operations that each supports.

  • Input iterators : ==, !=, ++, *, ->
  • Output iterators : ++, *
  • Forward iterators : ==, !=, ++, *, ->
  • Bidirectional iterators : ==, !=, ++, --, *, ->
  • Random-access iterators : ==, !=, <, <=, >, >=, ++, --, +, +=, -, -=, -(two iterators), *, ->, iter[n] == * (iter + n)

Exercise 10.39:

What kind of iterator does a list have? What about a vector?

list have the Bidirectional iterators. vector have the Random-access iterators.

Exercise 10.40:

What kinds of iterators do you think copy requires? What about reverse or unique?

  • copy : first and second are Input iterators, last is Output iterators.
  • reverse : Bidirectional iterators.
  • unique : Forward iterators.

Exercise 10.41:

Based only on the algorithm and argument names, describe the operation that the each of the following library algorithms performs:

replace(beg, end, old_val, new_val); // replace the old_elements in the input range as new_elements.
replace_if(beg, end, pred, new_val); // replace the elements in the input range which pred is true as new_elements.
replace_copy(beg, end, dest, old_val, new_val); // copy the new_elements which is old_elements in the input range into dest.
replace_copy_if(beg, end, dest, pred, new_val); // copy the new_elements which pred is true in the input range into dest.