FStream several ways to open files, easy to use later

FStream Fout;
(1) Open the file as output, if the file does not exist to establish the file, if the file exists to set the length of the file to 0
Fout.open ("D:/1.txt", ofstream::out|ofstream::trunc);//cannot be used | |
if (!fout.is_open ())
{
Return
}


(2) Open the file in the output mode, if there is no file, then generate an empty file, if there is a file, then empty the file, when writing the file is the file pointer to the end of the file
Fout.open ("D:/1.txt", ofstream::out|ofstream::ate);//cannot be used | |
if (!fout.is_open ())
{
Return
}


(3) Open the file in the output mode, if there is no file, then generate an empty file, if there is a file, then append at the end of the file. When writing a file, the file pointer points to the end of the file
Fout.open ("D:/1.txt", ofstream::out|ofstream::app);//cannot be used | |
if (!fout.is_open ())
{
Return

}

C language version

FILE *pf=null;
Pf=fopen ("D:/1.txt", "r+"); r+ Open Read-write file, if the file does not exist open failed, if the file exists open file successfully
if (pf==null)
{
cout<<m_sfilepath<< "does not exist now re-create" <<endl;
}
if (pf==null)
{
Pf=fopen (M_sfilepath.c_str (), "w+"),//w+ open a read-write file, if the file exists then the file length is clear to zero, that is, the contents of the file disappears. If the file does not exist, the file is created.
cout<< "Recreate file" <<m_sFilePath<<endl;
if (pf==null)
{
Return
}
}

R opens the file as read-only, and the file must exist.
r+ Open the file as read-write, the file must be present.
W Open Write-only file, if the file exists then the file length is clear to 0, that is, the contents of the file will disappear. If the file does not exist, the file is created.
w+ Open a read-write file, if the file exists then the file length is clear to zero, that is, the contents of the file will disappear. If the file does not exist, the file is created.
A write-only file opens in an additional way. If the file does not exist, the file will be created, and if the file exists, the data written will be added to the end of the file, that is, the original content of the file will be retained. (EOF character reserved)
A + opens readable and writable files in an additional way. If the file does not exist, the file will be created, and if the file exists, the data written will be added to the end of the file, that is, the original content of the file will be retained. (the original EOF character is not preserved)

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

FStream several ways to open files, easy to use later