cppType errorMedium

std::accumulate integer default truncates float sum

Time: 0:00

BugFind the bug and fix the code

What it should do

Sum vector of floating point numbers. Example: accumulateFloatValues([1.5, 2.5]) -> 4.0

What happens instead

Result truncated to integer 3.0 instead of decimal 4.0

#include <iostream>
#include <vector>
#include <numeric>

double accumulateFloatValues(std::vector<double> vals) {
    // 0 is int literal; std::accumulate infers accumulator type T as int!
    return std::accumulate(vals.begin(), vals.end(), 0);
}

int main() {
    std::cout << accumulateFloatValues({1.5, 2.5}) << std::endl;
    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 type errors pattern

Totals that concatenate, sorts that put 10 before 9, comparisons that refuse to run.

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#include <iostream> #include <vector> #include <numeric> double accumulateFloatValues(std::vector<double> vals) { // 0 is int literal; std::accumulate infers accumulator type T as int! return std::accumulate(vals.begin(), vals.end(), 0); } int main() { std::cout << accumulateFloatValues({1.5, 2.5}) << std::endl; return 0; }

std::accumulate integer default truncates float sum

What it should do

What happens instead

More type errors to practise

std::accumulate integer default truncates float sum

What it should do

What happens instead

More type errors to practise