xforevertink

I'm trying to only change the code within the function "partial_sum". but it doesn't seem to return the total. What am i doing wrong?

Code:

#include<iostream>
#include<vector>
#include<exception>
#include<stdexcept>
#include<string>

using namespace std;

int partial_sum(vector<int> v, int n) {
	{  int  total = 0;
		for (int i = 0; i < v.size(); i++)
			total += v[i];
		return total;
		
	}
	
	return false;
}

bool compare_vectors(vector<int> v1, vector<int> v2);
string test(bool);
int partial_sum(vector<int>, int);


int main() {
	
    vector<int> v;
    v.push_back(4);
    v.push_back(20);
    v.push_back(-1000);
    v.push_back(300);
    v.push_back(1);
    v.push_back(20);
	v.push_back(1);
	
	bool exception_thrown = false;

    cout << "partial_sum() - Test 1: " << test(partial_sum(v, 1) == 4) << endl;
    cout << "partial_sum() - Test 2: " << test(partial_sum(v, 2) == 24) << endl;
	
    exception_thrown = false;
    try {
        partial_sum(v, 8);
    }
    catch (runtime_error& e) {
        exception_thrown = true;
    }
    cout << "partial_sum() - Test 3: " << test(exception_thrown) << endl;
	
}

bool compare_vectors(vector<int> v1, vector<int> v2) {
    if (v1.size() != v2.size()) return false;
	
    for (int i = 0; i < v1.size(); ++i) {
        if (v1[i] != v2[i]) return false;
    }
    return true;
}

string test(bool expression) {
    if (expression) return "Passed";
    else return "Failed";
}

bithub

I don't know what that return false is doing in the function, but that's wrong.

Also, what makes you say that partion_sum is not returning the correct total? You are never printing out the return of partion_sum, so how can you be sure?

xforevertink

Sorry, the code is a bit messy. :[

xforevertink

I'm trying to return the partial sum that the text below in the main function is asking for.
But it keeps coming out in the terminal as failed....

grumpy

You can remove the "return false;" from partial_sum() for a starter (and eliminate an extraneous pair of curly braces). However, that won't change the results - it's just tidying the code.

Your partial_sum() function loops over the whole vector, and ignores the second argument. With the vector v you have populated in main(), the function will always return -654.

However, the tests you're doing in main() imply that you expect different results than partial_sum() will do. You either need to fix the test cases, or change the function to do whatever it is you expect to happen.

Hussain Hani

also just to point out something, you should pass the vector as a constant reference

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iMalc

Your main problem is that you're reinventing the wheel instead of embracing the standard library.
First off, replace your partial_sum with std::accumulate, or at least use that within your partial_sum.
Second off replace compare_vectors with just using bool operator==(const vector&, const vector&), or failing that, at least use std::equal for part of it.

Turn your warning levels up too. You should have already been made aware of your unused parameter 'n' to partial_sum.

Of course it comes through as failed. No exception was thrown so exception_thrown is false, thus test returns "failed". Were you wanting it to return "failed" only if an exception was thrown?

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