String incompatibility issues c++ - c++

Question

I am trying to create a function that will take in a long string with " " and "," dividing different elements gained from a text file. "," represents a new line and " " represents the end of a number in the line. once split the strings should be part of an array.
string* splitstr(string text, string deli = " ")
{
int start = 0;
int end = text.find(deli);
string *numbers[end];
for (int i = 0; end != -1; i++)
{
numbers[i] = text.substr(start, end - start);
start = end + deli.size();
end = text.find(deli, start);
}
return numbers;
}
However I am facing a problem where I get this:
cannot convert 'std::string**' {aka 'std::__cxx11::basic_string<char>**'} to 'std::string*' {aka 'std::__cxx11::basic_string<char>*'} in return
How can I resolve this, or improve my function?
I was expecting to be able to store string elements in a string array and make the function return the array. I'm fairly new to programming and I started off with java so this logic might not work in c++.

Answer 1

You should avoid using arrays like this and instead use a vector
like as follows:
std::vector<std::string> splitstr(const std::string & text, const std::string & deli = " ")
{
int start = 0;
int end = text.find(deli);
std::vector<std::string> numbers;
for (int i = 0; end != -1; i++)
{
numbers.push_back(text.substr(start, end - start));
start = end + deli.size();
end = text.find(deli, start);
}
return numbers;
}
note this will not get the last item in the string if there is not a delimiter after it.

Answer 2

Use a combination of std::vector and std::string_view.
A string_view avoids the need to allocate new output strings, the caveat is that you can only use the split result if the original input string is still in memory.
#include <iostream>
#include <vector>
#include <string>
#include <string_view>
auto split(std::string_view string, std::string_view delimiters)
{
std::vector<std::string_view> substrings;
if (delimiters.size() == 0ul)
{
substrings.emplace_back(string);
return substrings;
}
auto start_pos = string.find_first_not_of(delimiters);
auto end_pos = start_pos;
auto max_length = string.length();
while (start_pos < max_length)
{
end_pos = std::min(max_length, string.find_first_of(delimiters, start_pos));
if (end_pos != start_pos)
{
substrings.emplace_back(&string[start_pos], end_pos - start_pos);
start_pos = string.find_first_not_of(delimiters, end_pos);
}
}
return substrings;
}
struct test_data_t
{
std::string input;
std::string delim;
};
int main()
{
using namespace std::string_view_literals;
std::vector<test_data_t> test_data
{
{ " ", " " },
{ "a", " " },
{ "aa", " " },
{ "a a", " " },
{ " a a", " " },
{ " a a", " " },
{ "a a ", " " },
{ "`The time has come,` the Walrus said, `To talk of many things : Of shoes -- and ships -- and sealing -- wax -- Of cabbages -- and kings -- And why the sea is boiling hot --And whether pigs have wings.`", "`, -.:" }
};
for (const auto& [input, delim] : test_data)
{
auto substrings = split(input, delim);
std::cout << substrings.size() << " : ";
bool comma = false;
for (const auto& substring : substrings)
{
if (comma) std::cout << ", ";
std::cout << substring;
comma = true;
}
std::cout << "\n";
}
return 0;
}