fopen()的参数

herocsz

参数有w+,w+b, wb+
它的解释是：使文件为0，长，或为读和写而打开。

我有些疑惑：符号+有什么意思？
还有w+b和wb+有什么区别？

gz80

lz可以看看下面页面的说明：
http://www.cplusplus.com/reference/clibrary/cstdio/fopen/

For the modes where both read and writing (or appending) are allowed (those which include a "+" sign) ...blablabla...

herocsz

还挺详细的，多谢ls的
mode
C string containing a file access modes. It can be:
"r" Open a file for reading. The file must exist.
"w" Create an empty file for writing. If a file with the same name already exists its content is erased and the file is treated as a new empty file.  
"a" Append to a file. Writing operations append data at the end of the file. The file is created if it does not exist.
"r+" Open a file for update both reading and writing. The file must exist.
"w+" Create an empty file for both reading and writing. If a file with the same name already exists its content is erased and the file is treated as a new empty file.
"a+" Open a file for reading and appending. All writing operations are performed at the end of the file, protecting the previous content to be overwritten. You can reposition (fseek, rewind) the internal pointer to anywhere in the file for reading, but writing operations will move it back to the end of file. The file is created if it does not exist.

herocsz

This additional "b" character can either be appended at the end of the string (thus making the following compound modes: "rb", "wb", "ab", "r+b", "w+b", "a+b") or be inserted between the letter and the "+" sign for the mixed modes ("rb+", "wb+", "ab+").

r+b和rb+
w+b和wb+
是一样的

ubuntuer

In order to open a file as a binary file, a "b" character has to be included in the mode string
原来这个b是指binary