求C语言中文件中字母的全称,该如何解决

求C语言中文件中字母的全称
在文件中“r”表示“read”,那“w”,"a","rb","wb","ab"？？？
希望哪位大牛可以帮下小弟我，不胜感激！

[解决办法]
这个算比较详细
http://blog.xd547.com/topics/c_fopen_mode?utm_source=rss&utm_medium=rss&utm_campaign=c_fopen_mode
[解决办法]
w----write
r----read
a----append
b----binary
[解决办法]
"r"
open text file for reading
"w"
create text file for writing; discard previous contents if any
"a"
append; open or create text file for writing at end of file
"r+"
open text file for update (i.e., reading and writing)
"w+"
create text file for update, discard previous contents if any
"a+"
append; open or create text file for update, writing at end
 
 If the mode includes b after the initial letter, as in "rb" or "w+b", that indicates a binary file.
[解决办法]
楼主要会自己谷歌。比如你这问题。搜索关键字应该fopen c
[解决办法]

探讨

"r"
open text file for reading
"w"
create text file for writing; discard previous contents if any
"a"
append; open or create text file for writing at end of file
"r+"
open text file for update ……

[解决办法]
额，只知道a是在文件末尾附加写，不晓得是append，学习了
[解决办法]
r:只读方式打开，文件指针指向文件头，如果不存在返回错误值；
r+:读写方式打开，文件指针指向文件头，如果不存在返回；
w:写方式打开，文件指针指向文件头，大小清零，如果不存在尝试创建；
w+:读写方式打开，文件指针指向文件头，大小清零，如果不存在尝试创建；
a:写方式打开，文件指针指向文件尾，如果不存在尝试创建；
a+:读写方式打开，文件指针指向文件尾，如果不存在尝试创建；
[解决办法]
The character string mode specifies the type of access requested for the file, as follows:

"r"

Opens for reading. If the file does not exist or cannot be found, the fopen call fails.

"w"

Opens an empty file for writing. If the given file exists, its contents are destroyed.

"a"

Opens for writing at the end of the file (appending) without removing the EOF marker before writing new data to the file; creates the file first if it doesn’t exist.

"r+"

Opens for both reading and writing. (The file must exist.)

"w+"

Opens an empty file for both reading and writing. If the given file exists, its contents are destroyed.

"a+"

Opens for reading and appending; the appending operation includes the removal of the EOF marker before new data is written to the file and the EOF marker is restored after writing is complete; creates the file first if it doesn’t exist.

When a file is opened with the "a" or "a+" access type, all write operations occur at the end of the file. The file pointer can be repositioned using fseek or rewind, but is always moved back to the end of the file before any write operation is carried out. Thus, existing data cannot be overwritten.

The "a" mode does not remove the EOF marker before appending to the file. After appending has occurred, the MS-DOS TYPE command only shows data up to the original EOF marker and not any data appended to the file. The "a+" mode does remove the EOF marker before appending to the file. After appending, the MS-DOS TYPE command shows all data in the file. The "a+" mode is required for appending to a stream file that is terminated with the CTRL+Z EOF marker.

When the "r+", "w+", or "a+" access type is specified, both reading and writing are allowed (the file is said to be open for “update”). However, when you switch between reading and writing, there must be an intervening fflush, fsetpos, fseek, or rewind operation. The current position can be specified for the fsetpos or fseek operation, if desired.

In addition to the above values, the following characters can be included in mode to specify the translation mode for newline characters:

t

Open in text (translated) mode. In this mode, CTRL+Z is interpreted as an end-of-file character on input. In files opened for reading/writing with "a+", fopen checks for a CTRL+Z at the end of the file and removes it, if possible. This is done because using fseek and ftell to move within a file that ends with a CTRL+Z, may cause fseek to behave improperly near the end of the file. 

Also, in text mode, carriage return–linefeed combinations are translated into single linefeeds on input, and linefeed characters are translated to carriage return–linefeed combinations on output. When a Unicode stream-I/O function operates in text mode (the default), the source or destination stream is assumed to be a sequence of multibyte characters. Therefore, the Unicode stream-input functions convert multibyte characters to wide characters (as if by a call to the mbtowc function). For the same reason, the Unicode stream-output functions convert wide characters to multibyte characters (as if by a call to the wctomb function).

b

Open in binary (untranslated) mode; translations involving carriage-return and linefeed characters are suppressed. 

If t or b is not given in mode, the default translation mode is defined by the global variable _fmode. If t or b is prefixed to the argument, the function fails and returns NULL. 

For more information about using text and binary modes in Unicode and multibyte stream-I/O, see Text and Binary Mode File I/O and Unicode Stream I/O in Text and Binary Modes.

c

Enable the commit flag for the associated filename so that the contents of the file buffer are written directly to disk if either fflush or _flushall is called.

n

Reset the commit flag for the associated filename to “no-commit.” This is the default. It also overrides the global commit flag if you link your program with COMMODE.OBJ. The global commit flag default is “no-commit” unless you explicitly link your program with COMMODE.OBJ.

Valid characters for the mode string used in fopen and _fdopen correspond to oflag arguments used in _open and _sopen, as follows.

Characters in mode String Equivalent oflag Value for _open/_sopen
 
a _O_WRONLY | _O_APPEND (usually _O_WRONLY | _O_CREAT | _O_APPEND) 
a+ _O_RDWR | _O_APPEND (usually _O_RDWR | _O_APPEND | _O_CREAT ) 
r _O_RDONLY 
r+ _O_RDWR 
w _O_WRONLY (usually _O_WRONLY | _O_CREAT | _O_TRUNC) 
w+ _O_RDWR (usually _O_RDWR | _O_CREAT | _O_TRUNC) 
b _O_BINARY 
t _O_TEXT 
c None 
n None 

查看更多 下一篇