.. _vectors-mixed-up-code-exercises: Mixed-Up Code Exercises ----------------------- Answer the following **Mixed-Up Code** questions to assess what you have learned in this chapter. .. tb-group:: :name: self_check .. tb-tab:: Q1 .. tb-parsons:: :name: vectors_p1 :no-indent: Construct a block of code that changes the first element of vec to a 6, multiplies the third element of vec by 2, and increments the last element of vec by 1 (in that order). This should work no matter what vec is. .. code-block:: cpp {{group}} vec[0] = 6; {{endgroup}} {{group}} vec[2] = vec[2] * 2; {{endgroup}} {{group}} last = vec.size() - 1; vec[last]++; {{endgroup}} {{distractor}} {{group}} vec[1] = 6; #distractor {{endgroup}} {{distractor}} {{group}} vec[0] == 6; #distractor {{endgroup}} {{distractor}} {{group}} vec[3] = vec[3] * 2; #distractor {{endgroup}} {{distractor}} {{group}} last = vec.size(); #distractor vec[last]++; {{endgroup}} .. tb-parsons:: :name: vectors_p2 :no-indent: Construct a block of code that creates a vector called digs whose elements are 7, 8, 7, 8. Then access elements to change the digs to contain the elements 7, 4, 7, 4. Important: Change the 8's to 4's in order of increasing index. .. code-block:: cpp {{group}} vector digs = {7, 8, 7, 8}; {{endgroup}} {{group}} digs[1] = 4; {{endgroup}} {{group}} digs.pop_back(); {{endgroup}} {{group}} digs.push_back(4); {{endgroup}} {{distractor}} {{group}} vector digs = {7, 8, 7, 8}; #distractor {{endgroup}} {{distractor}} {{group}} vector digs = [7, 8, 7, 8]; #distractor {{endgroup}} {{distractor}} {{group}} digs[2] = 4; #distractor {{endgroup}} {{distractor}} {{group}} digs.pop_back(4); #distractor {{endgroup}} .. tb-parsons:: :name: vectors_p3 :no-indent: Construct a block of code that creates a vector called nums whose elements are five 1's. Then make a copy of this vector called digits, and use vector operations to change digits to {1, 2, 3}. .. code-block:: cpp {{group}} vector nums (5, 1); {{endgroup}} {{group}} vector digits = nums; {{endgroup}} {{group}} digits.pop_back(); digits.pop_back(); {{endgroup}} {{group}} digits[1]++; digits[2] = digits[2] * 3; {{endgroup}} {{distractor}} {{group}} vector nums = {1, 1, 1, 1, 1}; #distractor {{endgroup}} {{distractor}} {{group}} vector nums = digits; #distractor {{endgroup}} {{distractor}} {{group}} digits.push_back(); #distractor digits.push_back(); {{endgroup}} {{distractor}} {{group}} digits[2]++; #distractor digits[3] = digits[3] * 3; {{endgroup}} .. tb-parsons:: :name: vectors_p4 :no-indent: Construct a block of code that loops over a vector called numbers and transforms the vector so each element is doubled. .. code-block:: cpp {{group}} vector numbers = {1, 2, 3, 4, 5}; {{endgroup}} {{group}} for (size_t i = 0; i < numbers.size(); i++) { {{endgroup}} {{group}} numbers[i] = numbers[i] * 2; {{endgroup}} {{group}} } {{endgroup}} {{distractor}} {{group}} vector numbers = {1, 2, 3, 4, 5}; #distractor {{endgroup}} {{distractor}} {{group}} for (size_t i = 1; i <= numbers.size(); ++i) { #distractor {{endgroup}} {{distractor}} {{group}} for (int i = 0; i < numbers.size(); i++) { #distractor {{endgroup}} {{distractor}} {{group}} numbers[i] * 2; #distractor {{endgroup}} .. tb-parsons:: :name: vectors_p5 :no-indent: Suppose you have the vector

 

            vector words = {"car", "cat", "switch", "princess"};

Construct a block of code that transforms the vector to

 

            vector words = {"c_ar", "c_at", "switch", "m_ario"}

.. code-block:: cpp {{group}} words.pop_back(); {{endgroup}} {{group}} words.push_back("mario"); {{endgroup}} {{group}} for (size_t i = 0; i < words.size(); ++i) { {{endgroup}} {{group}} for (size_t c = 0; c < words[i].size(); ++c) { {{endgroup}} {{group}} if (words[i][c] == 'a') { {{endgroup}} {{group}} words[i][c] = 'A'; {{endgroup}} {{group}} } } } {{endgroup}} {{distractor}} {{group}} words.pop_back("mario"); #distractor {{endgroup}} {{distractor}} {{group}} for (int i = 0; i < words.size(); ++i) { #distractor {{endgroup}} {{distractor}} {{group}} for (int c = 0; c < words[i].size(); ++c) { #distractor {{endgroup}} {{distractor}} {{group}} words[i][c] == 'A'; #distractor {{endgroup}} .. tb-parsons:: :name: vectors_p7 :no-indent: Suppose album has already been defined as

 

            vector album = {"imagine", "needy", "NASA", "bloodline", "fake smile", "bad idea", "make up", "ghostin", "in my head", "7 rings", "thank u, next", "break up with your girlfriend, i'm bored"}

Construct a block of code that counts how many songs in album start with b. .. code-block:: cpp {{group}} count = 0 {{endgroup}} {{group}} for (size_t i = 0; i < album.size(); i++) { {{endgroup}} {{group}} if (album[i][0] == 'b') { {{endgroup}} {{group}} ++count; {{endgroup}} {{group}} } } {{endgroup}} {{distractor}} {{group}} for (int i = 0; i < album.size(); i++) { #distractor {{endgroup}} {{distractor}} {{group}} if (album[i] == 'b') { #distractor {{endgroup}} {{distractor}} {{group}} if (album[i][1] == 'b') { #distractor {{endgroup}} {{distractor}} {{group}} count++ #distractor {{endgroup}} .. tb-parsons:: :name: vectors_p8 :no-indent: Suppose you have the following two vectors to describe the weekly forecast

 

            vector temps = {82.0, 76.8, 74.3, 58.8, 79.2, 73.4, 80.1}
            vector precip = {0.00, 0.30, 0.60, 0.90, 0.10, 0.20, 0.80}

Your family will go to the beach if the temperature at least 75 degrees and the chance of precipitation is less than 50%. Construct a block of code that counts how many days your family can hit the beach on your vacation. .. code-block:: cpp {{group}} count = 0; {{endgroup}} {{group}} for (int i = 0; i < 7; ++i) { {{endgroup}} {{group}} if (temps[i] >= 75.0 && precip[i] < 0.50) { {{endgroup}} {{group}} ++count; {{endgroup}} {{group}} } } {{endgroup}} {{distractor}} {{group}} for (size_t i = 1; i <= 7; ++i) { #distractor {{endgroup}} {{distractor}} {{group}} if (temps[i] > 75.0 && precip[i] <= 0.50) { #distractor {{endgroup}} {{distractor}} {{group}} count++ #distractor {{endgroup}} .. tb-parsons:: :name: vectors_p9 :no-indent: Suppose you have the following vector nouns

 

            vector nouns = {"cereal", "Cocoa Puffs", "Mario", "luigi", "Aerosmith"};

Construct a block of code that creates a vector of the proper nouns in nouns. Use the isupper function to check if a letter is uppercase. .. code-block:: cpp {{group}} vector proper = {}; {{endgroup}} {{group}} for (size_t i = 0; i < nouns.size(); ++i) { {{endgroup}} {{group}} if (isupper(nouns[i][0])) { {{endgroup}} {{group}} proper.push_back(nouns[i]); {{endgroup}} {{group}} } } {{endgroup}} {{distractor}} {{group}} if (isupper(nouns[i][1])) { #distractor {{endgroup}} {{distractor}} {{group}} proper.push_back(nouns[i][0]); #distractor {{endgroup}} {{distractor}} {{group}} proper.pop_back(nouns[i]); #distractor {{endgroup}} {{distractor}} {{group}} vector proper = {}; #distractor {{endgroup}} .. admonition:: Parsons exercise Suppose you have the following function how_many and vector exclamations :: int how_many (const vector& vec, char let) { int count = 0; for (size_t i = 0; i < vec.size(); i++) { for (size_t c = 0; c < vec[i].size(); c++) { if (vec[i][c] == let) { count++; } } } return count; } vector excl = {"what?!", "how???", "fine!", "STOP.", "yay!!!!!", "ugh...!"}; Construct a block of code that counts how many times ".", "!", and "?" occur in exclamations. Save the counts to a vector with "." count as the first element, "!" count as the second, and "?" count as the third. .. code-block:: text {{group}} vector punc = {'.', '!', '?'}; vector counts = {}; {{endgroup}} {{group}} for (int i = 0; i < punc.size(); ++i) { {{endgroup}} {{group}} counts.push_back(how_many(excl, punc[i])); {{endgroup}} {{group}} } {{endgroup}} {{distractor}} {{group}} vector punc = {".", "!", "?"}; #distractor vector counts = {}; {{endgroup}} {{distractor}} {{group}} for (int i = 0; i < excl.size(); ++i) { #distractor {{endgroup}} {{distractor}} {{group}} counts.push_back(how_many(excl, i)); #distractor {{endgroup}}