Reversing a string using only iostream, fstream, string and vector - c++11

Question

I just started working with C++ about a week ago so I don't know much about the language. I am working on creating a program that inputs a text file and then reverses all of the lines.
So an input of:
"abc"
"123"
Would be:
"cba"
"321"
I can figure out how to input the lines from the file, but I am having trouble with my reverse function. I have tried to just print out each individual character as a string using substring, starting from length - 1 and ending at 0. But this does not seem to be working. When I run the program, I get these errors that I don't understand.. Any ideas as to what is going wrong?
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;
void reverse(string input) {
for((int x=input.length()-1); x=0; x--)
cout << input.substr(x);
}
cout << endl;
}
int main()
{
string line;
ifstream myFile;
myFile.open("reverse_input.txt");
while(getline(myFile, line)) {
reverse(line);
}
return 0;
}

Answer 1

There are couple syntax errors in your code that the compiler was complaining
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;
void reverse(string input) {
for( unsigned int x= (input.length()-1); x>=0; x--) { //Missing {, extra (), >= insteadof = 0
cout << input[x] << flush;
}
cout << endl;
}
int main()
{
string line;
ifstream myFile;
myFile.open("reverse_input.txt");
while(getline(myFile, line)) {
reverse(line);
}
return 0;
}