The Ring programming language version 1.2 book - Part 15 of 84

Ring Documentation, Release 1.2
• fwrite()
• fexists()
26.1 Read() Function
We can read the file content using the Read() function
Syntax:
Read(cFileName) ---> String contains the file content
Example:
see read("myfile.txt")
The read function can read binary files too
Example:
see read("myapp.exe")
26.2 Write() Function
We can write string to file using the Write() function
The write function can write binary data to binary files.
Syntax:
Write(cFileName,cString) # write string cString to file cFileName
Example:
# copy file
cFile = read("ring.exe")
write("ring2.exe",cFile)
26.3 Dir() Function
We can get the folder contents (files & sub folders) using the Dir() function.
Syntax:
Dir(cFolderPath) ---> List contains files & sub folders.
This function returns a list and each list item is a list of two items
• File/sub folder name
• Type (0 = File , 1 = Folder/Directory)
Example:
26.1. Read() Function 120

see "Testing DIR() " + nl
mylist = dir("C:myfolder")
for x in mylist
if x[2]
see "Directory : " + x[1] + nl
else
see "File : " + x[1] + nl
ok
next
see "Files count : " + len(mylist)
26.4 Rename() Function
We can rename files using the Rename() function
Syntax:
Rename(cOldFileName,cNewFileName)
Example:
rename("file.txt","help.txt")
26.5 Remove() Function
We can delete a file using the Remove() function
Syntax:
Remove(cFileName)
Example:
remove("test.txt")
26.6 Fopen() Function
We can open a file using the Fopen() function
Syntax:
Fopen(cFileName,cMode) ---> File Handle
Mode Description
“r” Reading (The file must exist)
“w” Writing (create empty file / overwrite)
“a” Appends (create file if it doesn’t exist)
“r+” update (reading/writing)
“w+” Create empty file (reading/writing)
“a+” reading & appending
26.4. Rename() Function 121

26.7 Fclose() Function
When we open a file using fopen() function, we can close it using the Fclose() function
Syntax:
Fclose(file handle)
26.8 Fflush() Function
We can flushes the output buffer of a stream using the Fflush() function
Syntax:
Fflush(file handle)
26.9 Freopen() Function
We can open another file using the same file handle and at the same file close the old file
Syntax:
Freopen(cFileName,cMode,file handle) ---> file handle
Example:
freopen("myprogoutput.txt","w+",stdout)
see "welcome" + nl
for x = 1 to 10
see x + nl
next
/*
** Read : https://en.wikipedia.org/wiki/Device_file#Device_files
** The next code is not portable, we can use iswindows() before
** using it and we can write special code for each operating system.
*/
freopen("CON","w",stdout) # For Microsoft Windows
see "Done" + nl # print to stdout again
Output:
# Output to stdout
Done
# Output to file : myprogoutput.txt
welcome
1
2
3
4
5
6
7
26.7. Fclose() Function 122

8
9
10
26.10 Tempfile() Function
The function Tempfile() creates a temp. file (binary).
The file will be deleted automatically when the stream is closed
Syntax:
TempFile() ---> file handle
26.11 Tempname() Function
We can generate temp. file name using the Tempname() function
The generated name will be different from the name of any existing file
Syntax:
Tempname() ---> generated file name as string
26.12 Fseek() Function
We can set the file position of the stream using the Fseek() function
Syntax:
Fseek(file handle, nOffset, nWhence) ---> zero if successful
The next table presents the nWhence values
Value Description
0 Beginning of file
1 Current position
2 End of file
26.13 Ftell() Function
We can know the current file position of a stream using the Ftell() function
Syntax:
Ftell(file handle) ---> file position as number
26.10. Tempfile() Function 123

26.14 Rewind() Function
We can set the file position to the beginning of the file using the Rewind() function
Syntax:
Rewind(file handle)
26.15 Fgetpos() Function
We can get handle to the current file position using the Fgetpos() function
Syntax:
Fgetpos(file handle) ---> position handle
26.16 Fsetpos() Function
We can set the current file position using the Fgetpos() function
Syntax:
Fsetpos(file handle,position handle)
26.17 Clearerr() Function
We can clear the EOF error and the error indicators of a stream using the clearerr() function
Syntax:
Clearerr(file handle)
26.18 Feof() Function
We can test the end-of-file indicator using the Feof() function
Syntax:
Feof(file handle) ---> returns 1 if EOF and 0 if not
26.19 Ferror() Function
We can test the error indicator of a given stream using the Ferror() function
Syntax:
Ferror(file handle) ---> returns 1 if error and 0 if not
26.14. Rewind() Function 124

26.20 Perror() Function
We can print error message to the stderr using the Perror() function
Syntax:
Perror(cErrorMessage)
26.21 Fgetc() Function
We can get the next character from the stream using the Fgetc() function
Syntax:
Fgetc(file handle) ---> returns character or EOF
26.22 Fgets() Function
We can read new line from the stream using the Fgets() function
Syntax:
Fgets(file handle,nSize) ---> string
The function stop when nSize characters are read, new line character is read or EOF.
26.23 Fputc() Function
We can write a character to the stream using the Fputc() function
Syntax:
Fputc(file handle,cChar)
26.24 Fputs() Function
We can write a string to the stream using the Fputs() function
Syntax:
Fputs(file handle,cString)
26.25 Ungetc() Function
We can push a character to the stream using the Ungetc() function
The character will be available for the next read
Syntax:
26.20. Perror() Function 125

Ungetc(file handle,character)
26.26 Fread() Function
We can read data from a stream using the Fread() function
Syntax:
Fread(file handle,nSize)
26.27 Fwrite() Function
We can write data to a stream using the Fwrite() function
Syntax:
Fwrite(file handle,cString)
26.28 Fexists() Function
We can check if a ﬁle exists using the Fexists() function
Syntax:
Fexists(cFileName) ---> returns 1 if the file exists
Example:
see fexists("b:mahmoudappsringring.exe") + nl +
fexists("b:mahmoudappsringring2.exe") + nl
Output:
1
0
26.29 Example
The next program test some of the ﬁle functions
See "Testing file functions" + nl
See "open file" + nl
fp = fopen("testss65.ring","r")
See "reopen" + nl
fp = freopen("testss78.ring","r",fp)
See "close file" + nl
fclose(fp)
see "temp file" + nl
26.26. Fread() Function 126

fp = tempfile()
fclose(fp)
see "temp name" + nl
see tempname() + nl
remove("testsmytest1.txt")
write("teststest1.txt","hello")
rename("teststest1.txt","testsmytest2.txt")
see "print file" + nl
fp = fopen("testsfile.ring","r")
r = fgetc(fp)
while isstring(r)
see r
r = fgetc(fp)
end
fclose(fp)
see nl+"print line from the file" + nl
fp = fopen("testsfile.ring","r")
r = fgets(fp,100)
see r
fclose(fp)
fp = fopen("testsmyfile.txt","rw+")
fseek(fp,0,2) # goto end of file
fputc(fp,"t")
fputc(fp,"e")
fputc(fp,"s")
fputc(fp,"t")
fputs(fp,"test2")
fclose(fp)
see "print file" + nl
see read("testsmyfile.txt")
fp = fopen("testsmyfile.txt","r")
see "testing ungetc() " + nl
for x = 1 to 3
r = fgetc(fp)
see r + nl
ungetc(fp,r)
next
fclose(fp)
see "testing fread() " + nl
fp = fopen("ring.exe","r")
r = fread(fp,100)
see r + nl
fclose(fp)
see "testing fwrite() " + nl
fp = fopen("testsmyfile.txt","wb")
fwrite(fp,r)
fclose(fp)
26.29. Example 127

CHAPTER
TWENTYSEVEN
SYSTEM FUNCTIONS
In this chapter we are going to learn about the system functions
• System()
• SysGet()
• IsMSDOS()
• IsWindows()
• IsWindows64()
• IsUnix()
• IsMacOSX()
• IsLinux()
• IsFreeBSD()
• IsAndroid()
• Windowsnl()
• Get Command Line Arguments
• Get Active Source File Name
• CurrentDir()
• ExeFileName()
• ChDir()
• ExeFolder()
• Version()
27.1 System() Function
We can execute system commands using the system() function
Syntax:
System(cCommand)
Example:
System("myapp.exe") # Run myapp.exe
System("ls") # print list of files
128

27.2 SysGet() Function
We can get environment variables using the Get() function
Syntax:
SysGet(cVariable)
Example:
see sysget("path") # print system path information
27.3 IsMSDOS() Function
We can check if the operating system is MSDOS or not using the IsMSDOS() function
Syntax:
IsMSDOS() ---> Returns 1 if the operating system is MS-DOS, Returns 0 if it's not
27.4 IsWindows() Function
We can check if the operating system is Windows or not using the IsWindows() function
Syntax:
IsWindows() ---> Returns 1 if the operating system is Windows, Returns 0 if it's not
27.5 IsWindows64() Function
We can check if the operating system is Windows 64bit or not using the IsWindows64() function
Syntax:
IsWindows64() ---> Returns 1 if the operating system is Windows64, Returns 0 if it's not
27.6 IsUnix() Function
We can check if the operating system is Unix or not using the IsUnix() function
Syntax:
IsUnix() ---> Returns 1 if the operating system is Unix, Returns 0 if it's not
27.7 IsMacOSX() Function
We can check if the operating system is Mac OS X or not using the IsMacOSX() function
Syntax:
27.2. SysGet() Function 129

The Ring programming language version 1.2 book - Part 15 of 84

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The Ring programming language version 1.2 book - Part 15 of 84