JuniorTheoryCommon

What does the program print?

C++

#include <iostream>

int main() {
    int a = 0;
    for (int i = 0; i <= 5; ++i) { ++a; }
    int b = 0;
    for (int i = 1; i < 5; ++i) { ++b; }
    std::cout << a << ' ' << b;
}

6 4

Expecting 5 4: <= lets i reach the bound, so the first loop runs for 0, 1, … 5, six values in all, not five.
Expecting 6 5: the second loop starts at 1, so i takes only the values 1 to 4, and the body runs four times.

How would you write a for loop whose body runs exactly n times?
What goes wrong if a loop like the first one reads the elements of a 5-element array?

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JuniorTheoryCommon

What does the program print?

C++

#include <iostream>

int main() {
    int a = 0;
    for (int i = 0; i <= 5; ++i) { ++a; }
    int b = 0;
    for (int i = 1; i < 5; ++i) { ++b; }
    std::cout << a << ' ' << b;
}

6 4

Expecting 5 4: <= lets i reach the bound, so the first loop runs for 0, 1, … 5, six values in all, not five.
Expecting 6 5: the second loop starts at 1, so i takes only the values 1 to 4, and the body runs four times.

How would you write a for loop whose body runs exactly n times?
What goes wrong if a loop like the first one reads the elements of a 5-element array?

Back to questions Open topic in roadmap →Answer it yourself — Quiz