C :: File Existence Check And Ask To Make Another File And Rename

I have this code to check if file exist already and its work, but what i need is : is to add feature to function to see if the file already exist open same file and rename it with another name ,probably file2

assume file name is "abc.c"

This scenario like this

User>>(provide file name)

Code>>(check if file already exist show msg:

"File already (abc.c) exist would you like to create another file and rename it ("abc2.c") "maybe it need loop to search directory "????

User>>if press yes ok it will make another file with another name but if no exit the function and dont create another file

Code: // function to check file existence and here what i need to add the feature above

int fExist(const char* fn){
struct stat buffer;
int exist = stat(fn,&buffer);
if(exist == 0)

[Code] .....