cppScope errorMedium

Unexpected crash after function exit with lambda

Time: 0:00

BugFind the bug and fix the code

What it should do

Process data using a lambda function. Example: processDataLambda([1,2,3]) -> processed data.

What happens instead

Runtime error: segmentation fault

#include <vector>
#include <iostream>

void processDataLambda(const std::vector<int>& data) {
    std::vector<int> processedData;
    auto lambda = [&] (int value) {
        processedData.push_back(value * 2);
    };
    for (const auto& item : data) {
        lambda(item);
    }
}

int main() {
    std::vector<int> data = {1, 2, 3};
    processDataLambda(data);
    return 0;
}

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

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This bug belongs to the scope and closure bugs pattern

Every callback reports the last value, a counter never increments, UnboundLocalError on a variable you can see.

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#include <vector> #include <iostream> void processDataLambda(const std::vector<int>& data) { std::vector<int> processedData; auto lambda = [&] (int value) { processedData.push_back(value * 2); }; for (const auto& item : data) { lambda(item); } } int main() { std::vector<int> data = {1, 2, 3}; processDataLambda(data); return 0; }

Unexpected crash after function exit with lambda

What it should do

What happens instead

More scope and closure bugs to practise

Unexpected crash after function exit with lambda

What it should do

What happens instead

More scope and closure bugs to practise