How to approach .startswith() in C++? [duplicate] - c++

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This question already has answers here:
Check if one string is a prefix of another
(14 answers)
How do I check if a C++ std::string starts with a certain string, and convert a substring to an int?
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Closed 1 year ago.
I'm new to C++, learning from books and online video tutorials. I've been trying to get the following lines of code to work, without much success. Basically, trying to find a C++ equivalent to python'a .startswith() or "in".
In python, what I'm trying to achieve would look like this:
names = ["John","Mary","Joanne","David"]
for n in names:
if n.startswith("J"):
print(n)
In javascript, the syntax would be quite similar (there are better ways of doing this, but I'm trying to keep the lines of code close to python's):
const names = ["John","Mary","Joanne","David"];
for (let n of names) {
if (n.startsWith("J")) {
console.log(n);
}
So, I assumed things would work similarly in C++, right?
vector <string> names {"John","Mary","Joanne","David"};
for (auto n: names) {
if (n[0] == "J") {
cout << n << endl;
}
As I've just started learning about pointers, I might be getting confused between types / values / addresses, apologies for this.
What's the best way to solve this please? Alternatively, how should I find a way to mimic what "in" does in python, but for C++?
names = ["John","Mary","Joanne","David"]
for n in names:
if "J" in n:
print(n)
Thanks!