Strings - can someone tell me the error in this program || note- I am new to strings and I want to know what is wrong with this

Question

#include <iostream> //to find the length of a string

using namespace std;

int countstring(char a[])
{
int count =0;
for(int i =0;a[i]!='/0';i++)
{
count++;
}
return count;
}

int main()
{
char a[100];int c =0;
cout<<"Enter the string";cin.getline(a,100);

c =countstring(a);
cout<<"The length of the string is"<<c;
return 0;
}

Answer 1

Thank you so much I got it

Answer 2

Is that all like I mean ,am I accepting and storing it in a character array?