C++获取文件夹所有文件，并rename重命名

#include<iostream>
#include<io.h>
#include<cstdlib>
#include<string>
using namespace std;

int  main()
{
string newname = "C:\\Users\\LYH\\Desktop\\rename\\rename\\test\\image_disciple_";
int num = 1099;

_finddata_t file;
long lf;
if((lf = _findfirst("C:\\Users\\LYH\\Desktop\\rename\\rename\\test\\*.*", &file))==-1l)//_findfirst返回的是long型; long __cdecl _findfirst(const char *, struct _finddata_t *)
cout<<"文件没有找到!\n";
else
{
//_findnext( lf, &file );
cout<<"\n文件列表:\n";
while( _findnext( lf, &file ) == 0 )//int __cdecl _findnext(long, struct _finddata_t *);如果找到下个文件的名字成功的话就返回0,否则返回-1
{
char cnum[5] = "";
cout<<file.name<< "  ";

++num;
_itoa(num,cnum,10);

newname += cnum;
newname += ".png";

string oldname = file.name;
oldname = "C:\\Users\\LYH\\Desktop\\rename\\rename\\test\\" + oldname;
int c = rename(oldname.c_str(),newname.c_str());
cout<<newname.c_str()<<"  ";

if ( c == 0 )
puts ( "File successfully renamed" );
else
perror( "Error renaming file" );

newname = "image_disciple_";
cout<<endl;

}
}
_findclose(lf);
system("pause");
return 0;
}