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1. The loop below should add up the five scores. Which change fixes the out-of-bounds read? ``

cpp
vector<int> v = {70, 85, 90, 60, 75};
int total = 0;
for (size_t i = 0; i <= v.size(); ++i) {
    total += v[i];
}

``

Change v[i] to v.at(i + 1)Change the condition to i < v.size()Start i at 1 instead of 0Change the condition to i < v.size() - 1

2. What goes wrong in this loop when v is empty? ``

cpp
vector<int> v;
int total = 0;
for (size_t i = 0; i < v.size() - 1; ++i) {
    total += v[i];
}

``

The loop never runs, because 0 < 0 is falsev[0] is always valid, so the loop only misses the last valuesize() returns an int, so v.size() - 1 is -1 and the loop stopsv.size() - 1 wraps to 18446744073709551615, so the test is true and v[0] is read from an empty vector

3. The smoothing loop below fails on its first pass. Which read goes outside the array? ``

cpp
vector<int> readings = {10, 20, 30, 40, 50};
for (int i = 0; i < static_cast<int>(readings.size()); ++i) {
    int left = readings[i - 1];
    int right = readings[i + 1];
    // ...
}

``

readings[i + 1] at i = 0 reads index 1, which is validout[i] is written with the wrong typereadings[i - 1] at i = 0 reads index -1, one box before the startThe division by 3 gives 0 for small readings

4. A program reads scores.data()[i] for i from 0 up to i <= scores.size() and prints total 380 with exit code 0. A classmate says the program is correct because the total is right. Which answer is correct?

The classmate is right, because 380 is the sum of the five scoresThe classmate is wrong, because the read at index 5 is undefined behaviour, and the right total in that run was luckThe classmate is right, because data() checks the index before it readsThe classmate is wrong, because -Wall would have printed a warning for this loop

5. What does this program print? ``

cpp
#include <cstddef>
#include <iostream>
#include <vector>
using namespace std;

int main() {
    vector<int> temps = {18, 21, 19, 24};
    size_t day = 0;
    cout << boolalpha << (day - 1 < temps.size()) << "\n";
}

``

truefalse10

Bounds debugging