cppLogic errorHard

Member initialization order mismatch with declaration

Time: 0:00

BugFind the bug and fix the code

What it should do

Initialize multiplier and base value in struct. Example: constructConfigPair(5) -> 10

What happens instead

Garbage value calculated because fields initialize in declaration order

#include <iostream>

struct ConfigPair {
    // Declaration order: factor is initialized before base!
    int factor;
    int base;

    ConfigPair(int b) : base(b), factor(base * 2) {}
};

int constructConfigPair(int b) {
    ConfigPair cp(b);
    return cp.factor;
}

int main() {
    std::cout << constructConfigPair(5) << std::endl;
    return 0;
}

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

⏱️0:00

Hints

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Hint 2

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Hint 3

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This bug belongs to the logic errors pattern

The wrong operator, an inverted condition, a formula the right way round but backwards.

Learn the logic errors pattern Step through your own code

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#include <iostream> struct ConfigPair { // Declaration order: factor is initialized before base! int factor; int base; ConfigPair(int b) : base(b), factor(base * 2) {} }; int constructConfigPair(int b) { ConfigPair cp(b); return cp.factor; } int main() { std::cout << constructConfigPair(5) << std::endl; return 0; }

Member initialization order mismatch with declaration

What it should do

What happens instead

More logic errors to practise

Member initialization order mismatch with declaration

What it should do

What happens instead

More logic errors to practise