Save selected characters in a string vector
I have to store it reasonably char
in std::vector
strings if conversion is considered.
Here's an example:
vector<string> f (vector<string> input)
{
vector<string> output;
for (int i=0; i<input.size(); i++) // vector iteration
{
for (int j=0;j<input[i].size(); j++) // string iteration
{
output.push_back(string(input[i].at(j))); // access to characters
}
}
return output;
}
input[i]
- this string
, a input[i].at(j)
- char
; so i converted it to string
before clicking on vector<string>
.
I am wondering what happened to this approach. In particular, the compiler error is beyond comprehension for me:
invalid conversion from '__gnu_cxx::__alloc_traits<std::allocator<char> >::value_type {aka char}' to 'const char*' [-fpermissive]
Edit:
f
should work like this.
Assume that the vector input
has 3 lines: {abcd,efdr,loab}
; then output
should extract all aormic characters such as:{abcdefdrloab}
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To fix changing your mistake
output.push_back(string(&input[i].at(j)));
from
output.push_back(string(input[i].at(j)));
Basically
**for (int i=0; i<input.size(); i++) \\vector iteration**
This is the wrong way to iterate. For containers, iterators should be used to iterate
Below is a string copied from one vector (using iterator and stl you can use copy_if or lambda)
#include <iostream>
#include <iterator>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;
vector<string> f (vector<string> input)
{
vector<string> output;
copy(input.begin(),input.end(),back_inserter(output));
return output;
}
int main()
{
vector<string> h{"hello"},x;
x=f(h);
copy(x.begin(),x.end(),ostream_iterator<string>(cout," "));
}
Output
hello Program ended with exit code: 0
But to answer your question and fix your code
Below is the modified code
#include <iostream>
#include <iterator>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;
vector<string> f (vector<string> input)
{
vector<string> output;
for (int i=0; i<input.size(); i++)
{
for (int j=0;j<input[i].size(); j++)
{
output.push_back(string(&input[i].at(j)));
}
}
return output;
}
vector<string> fi (vector<string> input)
{
vector<string> output;
copy(input.begin(),input.end(),back_inserter(output));
return output;
}
int main()
{
vector<string> h{"hello"},x,y;
x=fi(h);
y=f(h);
copy(x.begin(),x.end(),ostream_iterator<string>(cout," "));
copy(y.begin(),y.end(),ostream_iterator<string>(cout," "));
}
Output
hello hello ello llo lo o Program ended with exit code: 0
Solution after editing
#include <iostream>
#include <iterator>
#include<vector>
#include<string>
#include<algorithm>
#include <numeric>
using namespace std;
template<typename T, typename... Args>
void push_back_vec(std::vector<T>& v, Args&&... args)
{
(v.push_back(args), ...);
}
int main()
{
vector<string>x;
push_back_vec(x, "abc", "cds", "ma");
string a = accumulate(x.begin(), x.end(), string(""));
cout<<a;
}
Output
abccdsmaProgram ended with exit code: 0
Simpler format
#include <iostream>
#include <iterator>
#include<vector>
#include<string>
#include<algorithm>
#include <numeric>
using namespace std;
int main()
{
vector<string>x{"abc", "cds", "ma"},a;
a.push_back(accumulate(x.begin(), x.end(), string("")));
copy(a.begin(),a.end(),ostream_iterator<string>(cout," "));
}
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