C++ Finding the nth prime number - c++

Question

i am trying to find the nth prime number.
For example: input 1 - result 2 , input 2 - result 3, input 3-result 5...
My isprime function currently works but i couldnt figure it out, there must be something wrong, please help, thanks:)
/*
Finding the nth Prime Number
Yasin OSMAN
*/
//Including Libraries
#include <iostream>
using namespace std;
//Defining a global counter
int counter = 0;
/*
Defining Functions
*/
//isPrime Function (returns true if the given number is prime)
bool isPrime(int n) {
bool answer = true;
for (int i = 2; i < n; i++) {
if (n % i == 0) {
answer = false;
}
}
return answer;
}
int main() {
int userInput;
cout<<"Please indicate which prime number do you want to see: ";
cin>>userInput;
for(int i=0;i<=userInput;i++){
if(isPrime(counter)){
if(counter==userInput){
cout<<counter<<"th prime number is : "<<i<<endl;
}
counter++;
}
counter++;
}
return 0;
}

Answer 1

To improve the isPrime function:
numbers less than 2 won't be prime, so reject them first.
bool isPrime(int n) {
if (n < 2) return false; // add this line
bool answer = true;
for (int i = 2; i < n; i++) {
if (n % i == 0) {
answer = false;
}
}
return answer;
}
To improve the main function:
Increment the counter only if a prime number is found.
Count prime numbers found, then check the total number.
Check if the number, not the counter, is prime.
int main() {
int userInput;
cout<<"Please indicate which prime number do you want to see: ";
cin>>userInput;
for(int i=0, counter=0;counter<=userInput;i++){ // note: the global "counter" is shadowed here
if(isPrime(i)){
counter++;
if(counter==userInput){
cout<<counter<<"th prime number is : "<<i<<endl;
}
}
}
return 0;
}

Answer 2

Thanks to #MikeCAT
i changed my isPrime function for numbers that less than 2,
bool isPrime(int n) {
bool answer = true;
if(n<2){
answer=false;
return answer;
}
if(n>=2){
for (int i = 2; i < n; i++) {
if (n % i == 0) {
answer = false;
return answer;
}
}
return answer;
}
}
and i also made nthPrime a function,
int nthPrime(int n){
double i;
for(i=2;counter<n;i++){
if(isPrime(i)){
counter++;
}
}
return i-1;
}
and to display the result i used the following code :
int userInput;
cout<<"Please indicate which prime number do you want to see: ";
cin>>userInput;
cout<<counter<<"th prime number is : "<<nthPrime(userInput);
return 0;
Output Example : Please indicate which prime number do you want to see: 5
5th prime number is : 11