Check out example codes for "if file exist rename c#". It will help you in understanding the concepts better.
Code Example 1
int count = 1;
string fileNameOnly = Path.GetFileNameWithoutExtension(fullPath);
string extension = Path.GetExtension(fullPath);
string path = Path.GetDirectoryName(fullPath);
string newFullPath = fullPath;
while(File.Exists(newFullPath))
{
string tempFileName = string.Format("{0}({1})", fileNameOnly, count++);
newFullPath = Path.Combine(path, tempFileName + extension);
}
Learn ReactJs, React Native from akashmittal.com