Timestamp of file in c++

Question

i want to check a file to see if its been changed and if it is, then load it again.. for this, i started with the following code which is getting me nowhere...

#include <sys/types.h>
#include <sys/stat.h> 
#include <unistd.h>
#include <iostream>

using namespace std;

int main()
{
    struct stat st;
    int ierr = stat ("readme.txt", &st);
    if (ierr != 0) {
            cout << "error";
    }
    int date = st.st_mtime;
    while(1){
            int newdate = st.st_mtime;
            usleep(500000);
            if (newdate==date){
                    cout << "same file.. no change" << endl;
            }
            else if (newdate!=date){
                    cout << "file changed" << endl;
            }
    }
}

all the code does is print same file.. no change continuously.

Answer 1

That's because you're calling stat() outside the loop.

The result from stat() is correct at that particular moment. you need to call stat() again each time you want to check it.