具有变量的C ++文件/目录状态

Question

I'm trying to check if directory exist. I want to make it more reliable and I'm trying to use stat with predefined variable which check user name, but all the time I'm getting an error.

Here's userdir string output : /home/root/test

    string userdir="/home/"+user+"/test";

  struct stat st ;
  if(stat(userdir, &st) == 0)
    printf( "test directory exist\n" );
  else
    printf("test directory don't exist\n");

Answer 1

stat() takes a const char * , not an std::string :

if (stat(userdir.c_str(), &st) == 0)
//               ^^^^^^^

Answer 2

If string is std::string then you need to call stat(userdir.c_str(), &st) - stat takes a C style string, not a C++ one.

Minimal example:

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

int main() {
  const std::string dir="/tmp";
  struct stat st;

  return stat(dir, &st); // Error

  return stat(dir.c_str(), &st); // Correct
}