File_Type fopen (String_Type f, String_Type m)
The fopen function opens a file f according to the mode
string m. Allowed values for m are:
"r" Read only
"w" Write only
"a" Append
"r+" Reading and writing at the beginning of the file.
"w+" Reading and writing. The file is created if it does not
exist; otherwise, it is truncated.
"a+" Reading and writing at the end of the file. The file is created
if it does not already exist.
In addition, the mode string can also include the letter 'b'
as the last character to indicate that the file is to be opened in
binary mode.
Upon success, fopen a File_Type object which is meant to
be used in other operations that require an open file. Upon
failure, the function returns NULL.
The following function opens a file in append mode and writes a
string to it:
define append_string_to_file (file, str)
{
variable fp = fopen (file, "a");
if (fp == NULL) verror ("%s could not be opened", file);
() = fputs (string, fp);
() = fclose (fp);
}
Note that the return values from fputs and fclose are
ignored.
There is no need to explicitly close a file opened with fopen.
If the returned File_Type object goes out of scope, S-Lang
will automatically close the file. However, explicitly closing a
file after use is recommended.
- slangrtl
-
clearerr,
close,
fclose,
fdopen,
feof,
ferror,
fflush,
fgets,
fgetslines,
fileno,
fprintf,
fputs,
fread,
fseek,
ftell,
fwrite,
isatty,
mkdir,
open,
pclose,
popen,
printf,
system
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