Intro to C++

The below is the code I added, then I got an mismatched above. Ineed your great experties to solve this problem.
Could you find what I missed?
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
float squareRoot(float s) {
float xn;
if (s == 0.0) {
return 0.0;
}
xn = s / 2.0;
int counter =
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