如何检查字符串中的换行？

String str = "This is a string\nwith a newline";
boolean containsNewline = str.contains("\n");

import re

str = "This is a string\nwith a newline"
containsNewline = re.search(r'\n', str)

#include <iostream>
using namespace std;

int main() {
    string str = "This is a string\nwith a newline";
    bool containsNewline = false;
    
    for (char c : str) {
        if (c == '\n') {
            containsNewline = true;
            break;
        }
    }
    
    cout << "Contains newline: " << (containsNewline ? "true" : "false") << endl;
    return 0;
}