whatever i use as inputs, outputs are all zeros - c++

Question

This is a question i am working on:
Prompt the user to enter five numbers, being five people's weights. Store the numbers in a vector of doubles. Output the vector's numbers on one line, each number followed by one space.
Also output the total weight, by summing the vector's elements.
Also output the average of the vector's elements.
Also output the max vector element.
So far this is the code i have
#include <iostream>
#include <vector>
using namespace std;
int main() {
const int NEW_WEIGHT = 5;
vector<float> inputWeights(NEW_WEIGHT);
int i = 0;
float sumWeight = 0.0;
float AverageWeight = 1.0;
int maxWeight = 0;
int temp = 0;
for (i = 0; i < NEW_WEIGHT; i++){
cout << "Enter weight "<< i+1<< ": ";
cout << inputWeights[i]<< endl;
cin>> temp;
inputWeights.push_back (temp);
}
cout << "\nYou entered: ";
for (i =0; i < NEW_WEIGHT- 1; i++) {
cout << inputWeights.at(i)<< " ";
}
cout<< inputWeights.at(inputWeights.size() - 1) << endl;
for (i =0; i < NEW_WEIGHT; i++){
sumWeight += inputWeights.at(i);
}
cout <<"Total weight: "<< sumWeight<< endl;
AverageWeight = sumWeight / inputWeights.size();
cout <<"Average weight: "<< AverageWeight<< endl;
maxWeight= inputWeights.at(0);
for (i =0; i < NEW_WEIGHT- 1; i++){
if (inputWeights.at(i) > maxWeight){
maxWeight = inputWeights.at(i);
}
}
cout<< "Max weight: "<< maxWeight << endl;
return 0;
}
When i run this code, whatever inputs i use(for the cin>>(...)), i get all zero's as output and i do not know why. can i get some help please.
update
cleaned up the code a little by getting rid of the cout<< inputWeights[i]<< endl;
and by adjusting vector inputWeights; at the beginning of the program.But the outputs are still not exactly what they are supposed to be. Instead, only the first 2 inputted values make it as outputs. Any reason why? thanks
update this is the right or correct code. Hope it helps someone in future.
#include <iostream>
#include <vector>
using namespace std;
int main() {
const int NEW_WEIGHT = 5;
vector <float> inputWeights;
int i = 0;
float sumWeight = 0.0;
float AverageWeight = 1.0;
float maxWeight = 0.0;
float temp = 0.0;
for (i = 0; i < NEW_WEIGHT; i++){
cout << "Enter weight "<< i+1<< ": "<< endl;
cin>> temp;
inputWeights.push_back (temp);
}
cout << "\nYou entered: ";
for (i =0; i < NEW_WEIGHT- 1; i++){
cout << inputWeights.at(i)<< " ";
}
cout<< inputWeights.at(inputWeights.size() - 1) << endl;
for (i =0; i < NEW_WEIGHT; i++){
sumWeight += inputWeights.at(i);
}
cout <<"Total weight: "<< sumWeight<< endl;
AverageWeight = sumWeight / inputWeights.size();
cout <<"Average weight: "<< AverageWeight<< endl;
maxWeight= inputWeights.at(0);
for (i =0; i < NEW_WEIGHT- 1; i++){
if (inputWeights.at(i) > maxWeight){
maxWeight = inputWeights.at(i);
}
}
cout<< "Max weight: "<< maxWeight << endl;
return 0;
}

Answer 1

You're making a vector of size 5:
const int NEW_WEIGHT = 5;
vector<float> inputWeights(NEW_WEIGHT);
// == 0, 0, 0, 0, 0
Then, in your input loop, you're adding new values to the end:
inputWeights.push_back (42);
// == 0, 0, 0, 0, 0, 42
Then you're outputting the first five elements which were always zero.
You need to choose one thing or the other: either set the size of the vector at the start of the program, or grow the vector with push_back for as long as there's input. Both are valid options.
You can clean up your code and fix the problems by adopting modern C++ (as in, C++11 and later) idiom. You don't need to fill your code with for(int i = 0; i < something; i++) any more. There's a simpler way.
// Size fixed in advance:
vector<float> weights(NUM_WEIGHTS);
for (auto& weight : weights) { // note it's `auto&`
cout << "\nEnter next weight: ";
cin >> weight; // if it was plain `auto` you'd overwrite a copy of an element of `weight`
}
// Size decided by input:
vector<float> weights; // starts empty this time
cout << "Enter weights. Enter negative value to stop." << endl;
float in;
while (cin >> in) {
if(in < 0) {
break;
}
weights.push_back(in);
}
In either case, you can then play with the filled vector using another range-based for:
cout << "You entered: ";
for (const auto& weight : weights) {
cout << weight << " ";
}
You'll also need to remove the cout << inputWeights[i] << endl; line from your input loop if you resize the vector during input - as written you'd be reading elements which don't exist yet, and will probably get an array-index-out-of-bounds exception.

Answer 2

When you create define your inputWeights you are putting 5 items into it with default values.
vector<float> inputWeights(NEW_WEIGHT);
Change it to be just
vector<float> inputWeights;
And get rid of this line in your code or comment it out
cout << inputWeights[i]<< endl;

Answer 3

This is what you are looking for from the requirements of your program.
#include <vector>
#include <iostream>
int main() {
std::vector<double> weights;
double currentWeight = 0.0;
const unsigned numberOfWeights = 5;
std::cout << "Enter " << numberOfWeights << " weights" << std::endl;
unsigned i = 0;
for ( ; i < numberOfWeights; ++i ) {
std::cin >> currentWeight;
weights.push_back( currentWeight );
}
std::cout << "These are the weights that you entered: " << std::endl;
for ( i = 0; i < weights.size(); ++i ) {
std::cout << weights[i] << " ";
}
std::cout << std::endl;
double totalWeight = 0.0;
std::cout << "The total of all weights is: ";
for ( i = 0; i < weights.size(); ++i ) {
totalWeight += weights[i];
}
std::cout << totalWeight << std::endl;
std::cout << "The average of all the weights is: " << (totalWeight / numberOfWeights) << std::endl;
std::cout << "The max weight is: ";
double max = weights[0];
for ( i = 0; i < weights.size(); ++i ) {
if ( weights[i] > max ) {
max = weights[i];
}
}
std::cout << max << std::endl;
return 0;
}
The culprit to your problem for seeing all 0s as output is coming from these two lines of code:
const int NEW_WEIGHT = 5;
vector<float> inputWeights(NEW_WEIGHT);
which is the same as doing this:
vector<float> inputWeights{ 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
you are then looping through up to 5 elements using NEW_WEIGHT when it would be easier to use inputWeights.size() when traversing through containers.
Edit - Condensed Version
#include <vector>
#include <iostream>
int main() {
std::vector<double> weights;
double currentWeight = 0.0;
const unsigned numberOfWeights = 5;
unsigned i = 0;
std::cout << "Enter " << numberOfWeights << " weights" << std::endl;
for ( ; i < numberOfWeights; ++i ) {
std::cin >> currentWeight;
weights.push_back( currentWeight );
}
double totalWeight = 0.0;
double max = weights[0];
std::cout << "These are the weights that you entered: " << std::endl;
for ( i = 0; i < weights.size(); ++i ) {
std::cout << weights[i] << " "; // Print Each Weight
totalWeight += weights[i]; // Sum The Weights
// Look For Max Weight
if ( weights[i] > max ) {
max = weights[i];
}
}
std::cout << std::endl;
std::cout << "The total of all weights is: " << totalWeight << std::endl;
std::cout << "The average of all the weights is: " << (totalWeight / numberOfWeights) << std::endl;
std::cout << "The max weight is: " << max << std::endl;
return 0;
}