How can I get around the use of VLAs? - c++

Question

I have made some code and need to make the length of an array the same as a user input:
#include <iostream>
#include <string>
using namespace std;
void abrev(string word) {
int lastChar = word.length();
if (lastChar > 10) {
cout << word[0];
cout << lastChar - 2;
cout << word[lastChar - 1] << endl;
} else {
cout << word << endl;
}
}
int main() {
int n;
cin >> n;
string words[n];
for (int i = 0; i <= n - 1; i++) {
cin >> words[i];
}
for (int i = 0; i <= n - 1; i++) {
abrev(words[i]);
}
return 0;
}
I don't really know what I could possibly do, I have no ideas. I was using a compiler that just side steps this problem, so I didn't realize it until I submitted this code to codeforces.com, in which I got these errors:
Can't compile file:
program.cpp
program.cpp(20): error C2131: expression did not evaluate to a constant
program.cpp(20): note: failure was caused by a read of a variable outside its lifetime
program.cpp(20): note: see usage of 'n'
program.cpp(23): warning C4552: '>>': operator has no effect; expected operator with side-effect
Also I don't think the last error has anything to do with it, if you could help with that to that would be awesome!
Thankful for any help!

Answer 1

It's mostly duplicated, to resolve the error, it's easy to fix it with std::vector
Since the function abrev doesn't change the argument, it's better to use a const reference.
#include <iostream>
#include <string>
#include <vector>
using namespace std;
void abrev(const string& word) {
int lastChar = word.length();
if (lastChar > 10) {
cout << word[0];
cout << lastChar - 2;
cout << word[lastChar - 1] << endl;
} else {
cout << word << endl;
}
}
int main() {
int n;
cin >> n;
std::vector<std::string> words(n);
for (int i = 0; i <= n - 1; i++) {
cin >> words[i];
}
for (int i = 0; i <= n - 1; i++) {
abrev(words[i]);
}
return 0;
}