Pattern debugging

Questions 1 to 5 of 6

1. 1. This program should print a diamond for n = 3. It prints 6 rows, and the bottom half repeats the widest row. Which line is the bug? ``cpp for (int i = 1; i <= n; ++i) { std::cout << std::string(n - i, ' ') << std::string(2 * i - 1, '*') << '\n'; } for (int i = n; i >= 1; --i) { std::cout << std::string(n - i, ' ') << std::string(2 * i - 1, '*') << '\n'; } ``

   The first loop, for (int i = 1; i <= n; ++i), because it prints the top half too earlyThe star count std::string(2 * i - 1, '*'), because it gives one star too manyThe space count std::string(n - i, ' '), because it puts the shape one column too far rightThe second loop's start, int i = n, because it prints the widest row a second time
2. 2. A pyramid for n = 4 should have rows of 1, 3, 5 and 7 stars, with a single star in the middle of each row. This program prints ** as its top row. Which line is the bug? ``cpp for (int i = 1; i <= n; ++i) { std::cout << std::string(n - i, ' ') << std::string(2 * i, '*') << '\n'; } ``

   The loop limit i <= n, because it prints one row too manyThe space count std::string(n - i, ' '), because it puts the top row too far to the rightThe star count std::string(2 * i, '*'), which should be std::string(2 * i - 1, '*')The loop start int i = 1, which should start at i = 0
3. 3. This program should print the top half of a pyramid for n = 4, with rows of 1, 3, 5 and 7 stars. It prints only three rows, and the 7-star row is missing. Which line is the bug? ``cpp for (int i = 1; i < n; ++i) { std::cout << std::string(n - i, ' ') << std::string(2 * i - 1, '*') << '\n'; } ``

   std::string(2 * i - 1, '*') should be std::string(2 * i + 1, '*')std::string(n - i, ' ') has the wrong sign and should be std::string(i, ' ')The line should end with std::endl, so each row is flushedThe limit i < n stops before i reaches n, so the 7-star row never prints
4. 4. Put the five steps of the pattern debugging method in the order you follow them.

   Use the arrows to put the steps in order.

   1. 1.Count the rows and compare the count with the formula.↑↓
   2. 2.Read the loop that prints that row.↑↓
   3. 3.Find the first row that differs from the expected output.↑↓
   4. 4.Write the expected output first, before reading the broken code.↑↓
   5. 5.Change one thing, run the program again and compare.↑↓
5. 5. This program prints a diamond for n = 4. Each row ends with | instead of a newline, and the dots stand for spaces. What does it print? ``cpp #include <iostream> #include <string> int main() { const int n = 4; for (int i = 1; i <= n; ++i) { std::cout << std::string(n - i, '.') << std::string(2 * i - 1, '*') << '|'; } for (int i = n - 1; i >= 1; --i) { std::cout << std::string(n - i, '.') << std::string(2 * i - 1, '*') << '|'; } } ``

   ...*|..***|.*****|*******|.*****|..***|...*|...*|..***|.*****|*******|.*****|..***|...*|..***|.*****|*******|*******|.*****|..***|...*|....*|...***|..*****|.*******|..*****|...***|....*|