Vectors in C++ , bucket sort : Segmentation fault - c++

Question

In my code, I am trying to implement bucket sort and in my implementation I have tried using vectors, but unfortunately I end up with errors with respect to vector functions.
Code :
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
void bucket_sort(vector<float> & , int); //vector is passed by reference
int main(){
vector<float> array;
float element;
int count;
cout << "\nEnter the size of the vector : ";
cin >> count;
cout << "\nEnter the elements into the vector : ";
for(vector<float>::size_type i = 0 ; i < count ; i++){
cin >> element;
array[i].push_back(element);
}
bucket_sort(array , count);
}
void bucket_sort(vector<float> array, int count){
vector<float> bucket;
for(int i = 0 ; i < count ; i++){
int bucket_index = count * array[i];
bucket[bucket_index].push_back(array[i]);
}
for(int i = 0 ; i < count ; i++)
sort(bucket[i].begin() , bucket[i].end());
int index = 0;
for(int i = 0 ; i < count ; i++)
for(int j = 0 ; j < bucket[i].size() ; j++)
array[index++].push_back(bucket[i][j]);
}
Errors :
bucket_sort.cpp: In function ‘int main()’:
bucket_sort.cpp:24:12: error: request for member ‘push_back’ in ‘array.std::vector<_Tp, _Alloc>::operator[]<float, std::allocator<float> >(i)’, which is of non-class type ‘float’
array[i].push_back(element);
^
bucket_sort.cpp: In function ‘void bucket_sort(std::vector<float>, int)’:
bucket_sort.cpp:36:24: error: request for member ‘push_back’ in ‘bucket.std::vector<_Tp, _Alloc>::operator[]<float, std::allocator<float> >(((std::vector<float>::size_type)bucket_index))’, which is of non-class type ‘float’
bucket[bucket_index].push_back(array[i]);
^
bucket_sort.cpp:40:18: error: request for member ‘begin’ in ‘bucket.std::vector<_Tp, _Alloc>::operator[]<float, std::allocator<float> >(((std::vector<float>::size_type)i))’, which is of non-class type ‘float’
sort(bucket[i].begin() , bucket[i].end());
^
bucket_sort.cpp:40:38: error: request for member ‘end’ in ‘bucket.std::vector<_Tp, _Alloc>::operator[]<float, std::allocator<float> >(((std::vector<float>::size_type)i))’, which is of non-class type ‘float’
sort(bucket[i].begin() , bucket[i].end());
^
bucket_sort.cpp:45:33: error: request for member ‘size’ in ‘bucket.std::vector<_Tp, _Alloc>::operator[]<float, std::allocator<float> >(((std::vector<float>::size_type)i))’, which is of non-class type ‘float’
for(int j = 0 ; j < bucket[i].size() ; j++)
^
bucket_sort.cpp:46:19: error: request for member ‘push_back’ in ‘array.std::vector<_Tp, _Alloc>::operator[]<float, std::allocator<float> >(((std::vector<float>::size_type)(index ++)))’, which is of non-class type ‘float’
array[index++].push_back(bucket[i][j]);
^
bucket_sort.cpp:46:40: error: invalid types ‘float[int]’ for array subscript
array[index++].push_back(bucket[i][j]);
Edited code :
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
void bucket_sort(vector<float> & , int); //vector is passed by reference
int main(){
vector<float> array;
float element;
int count;
cout << "\nEnter the size of the vector : ";
cin >> count;
cout << "\nEnter the elements into the vector : ";
for(int i = 0 ; i < count ; i++){
cin >> element;
array.push_back(element);
}
bucket_sort(array , count);
cout << "\nSorted vector : ";
for(int i = 0 ; i < count ; i++)
cout << array[i] << " ";
}
void bucket_sort(vector<float>& array, int count){
vector<float> bucket[count];
for(int i = 0 ; i < count ; i++){
int bucket_index = count * array[i];
bucket[bucket_index].push_back(array[i]);
}
for(int i = 0 ; i < count ; i++)
sort(bucket[i].begin() , bucket[i].end());
int index = 0;
for(int i = 0 ; i < count ; i++)
for(int j = 0 ; j < bucket[i].size() ; j++)
array.push_back(bucket[i][j]);
}
Edit :
I have introduced the correction with respect to the push_back() but now upon running my code I hit a segmentation fault. Any suggestions?

Answer 1

push_back is method of vector, not element. To append element (with increasing vector size by 1) use array.push_back(123). To assign something to element use array[i] = 123.
If you want to fill vector using assignment, you have to resize vector first: array.resize(count).
To sort, wirte sort(array.begin() , array.end()).
bucket[i][j] is totally incorrect: bucket is one dimensional vector. You probably want bucket to be vector<vector<float>>.
for(int i = 0 ; i < count ; i++){
int bucket_index = count * array[i];
bucket[bucket_index].push_back(array[i]);
}
You have only count elements in bucket array but ask for count * array[i] element.

Answer 2

Your code have many problems.
Main problem is following:
You can not do this:
array[i].push_back(element);
You must do this instead:
array.push_back(element);
Later you do the same:
bucket[bucket_index].push_back(array[i]);
But this time, probably you need just:
bucket[bucket_index] = array[i];
Or if you want just to obtain a copy from vector called "array", you can just do:
bucket = array;
If you post comment what bucket_sort should do, I can provide future explanations.
Finally, I also would suggest you to add:
using MyVector = vector<float>;
Will safe you lots of typing.
Also you might define the function to use the vector by reference, because else it is copied and you probably do not want this:
void bucket_sort(MyVector &array, int count);

Answer 3

Instead of array[i].push_back(element), use array.push_back(element). Element will go at the position automatically as a for loop index.
So, at the end of loop, array will have count number of elements as desired by you.
Use this logic everywhere in the code.