The Ring programming language version 1.3 book - Part 17 of 88

1. Ring Documentation, Release 1.3
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9
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27.10 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
27.11 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
27.12 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
27.13 Ftell() Function
We can know the current file position of a stream using the Ftell() function
Syntax:
Ftell(file handle) ---> file position as number
27.10. Tempfile() Function 138

2. Ring Documentation, Release 1.3
27.14 Rewind() Function
We can set the file position to the beginning of the file using the Rewind() function
Syntax:
Rewind(file handle)
27.15 Fgetpos() Function
We can get handle to the current file position using the Fgetpos() function
Syntax:
Fgetpos(file handle) ---> position handle
27.16 Fsetpos() Function
We can set the current file position using the Fgetpos() function
Syntax:
Fsetpos(file handle,position handle)
27.17 Clearerr() Function
We can clear the EOF error and the error indicators of a stream using the clearerr() function
Syntax:
Clearerr(file handle)
27.18 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
27.19 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
27.14. Rewind() Function 139

3. Ring Documentation, Release 1.3
27.20 Perror() Function
We can print error message to the stderr using the Perror() function
Syntax:
Perror(cErrorMessage)
27.21 Fgetc() Function
We can get the next character from the stream using the Fgetc() function
Syntax:
Fgetc(file handle) ---> returns character or EOF
27.22 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.
27.23 Fputc() Function
We can write a character to the stream using the Fputc() function
Syntax:
Fputc(file handle,cChar)
27.24 Fputs() Function
We can write a string to the stream using the Fputs() function
Syntax:
Fputs(file handle,cString)
27.25 Ungetc() Function
We can push a character to the stream using the Ungetc() function
The character will be available for the next read
Syntax:
27.20. Perror() Function 140

4. Ring Documentation, Release 1.3
Ungetc(file handle,character)
27.26 Fread() Function
We can read data from a stream using the Fread() function
Syntax:
Fread(file handle,nSize)
27.27 Fwrite() Function
We can write data to a stream using the Fwrite() function
Syntax:
Fwrite(file handle,cString)
27.28 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
27.29 Example
The next program test some of the file functions
See "testing file functions" + nl
See "open file" + nl
fp = fopen(exefolder() + "../tests/scripts/s65.ring","r")
See "reopen" + nl
fp = freopen(exefolder() + "../tests/scripts/s78.ring","r",fp)
See "close file" + nl
fclose(fp)
see "temp file" + nl
27.26. Fread() Function 141

5. Ring Documentation, Release 1.3
fp = tempfile()
fclose(fp)
see "temp name" + nl
see tempname() + nl
remove(exefolder() + "../tests/scripts/mytest2.txt")
write(exefolder() + "../tests/scripts/tests1.txt","hello")
rename(exefolder() + "../tests/scripts/test1.txt",exefolder() +
"../tests/scripts/mytests2.txt")
see "print file" + nl
fp = fopen(exefolder() + "../samples/fromdoc/filefuncs.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(exefolder() + "../samples/fromdoc/filefuncs.ring","r")
r = fgets(fp,33)
see r + nl
fclose(fp)
fp = fopen(exefolder() + "../tests/scripts/test78.txt","w+")
fseek(fp,0,2) # goto end of file
fputc(fp,"t")
fputc(fp,"e")
fputc(fp,"s")
fputc(fp,"t")
fputs(fp,"tests2")
fclose(fp)
see "print file" + nl
see read(exefolder() + "../tests/scripts/test78.txt")
fp = fopen(exefolder() + "../tests/scripts/test78.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(exefilename(),"rb")
r = fread(fp,100)
see r + nl
fclose(fp)
see "testing fwrite() " + nl
fp = fopen(exefolder() + "../tests/scripts/test1.txt","wb")
fwrite(fp,r)
fclose(fp)
The next example print part of the content of a binary file
27.29. Example 142

6. Ring Documentation, Release 1.3
see "Testing: fread()" +" FileName: "+ exefilename() +nl +nl
fp = fopen(exefilename(),"rb")
r = fread(fp,800)
for n =1 to len(r)
if isprint(substr(r, n, 1))
see substr(r, n, 1)
else
see "."
ok
### 80 char per line
if n % 80 = 0
see nl
ok
next
fclose(fp)
27.29. Example 143

7. CHAPTER
TWENTYEIGHT
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()
28.1 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
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28.2 SysGet() Function
We can get environment variables using the Get() function
Syntax:
SysGet(cVariable)
Example:
see sysget("path") # print system path information
28.3 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
28.4 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
28.5 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
28.6 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
28.7 IsMacOSX() Function
We can check if the operating system is Mac OS X or not using the IsMacOSX() function
Syntax:
28.2. SysGet() Function 145

9. Ring Documentation, Release 1.3
IsMacOSX() ---> Returns 1 if the operating system is Mac OS X, Returns 0 if it's not
28.8 IsLinux() Function
We can check if the operating system is Linux or not using the IsLinux() function
Syntax:
IsLinux() ---> Returns 1 if the operating system is Linux, Returns 0 if it's not
28.9 IsFreeBSD() Function
We can check if the operating system is FreeBSD or not using the IsFreeBSD() function
Syntax:
IsFreeBSD() ---> Returns 1 if the operating system is FreeBSD, Returns 0 if it's not
28.10 IsAndroid() Function
We can check if the operating system is Android or not using the IsAndroid() function
Syntax:
IsAndroid() ---> Returns 1 if the operating system is Android, Returns 0 if it's not
28.11 Example
see "IsMSDOS() --> " + ismsdos() + nl
see "IsWindows() --> " + iswindows() + nl
see "IsWindows64() --> " + iswindows64() + nl
see "IsUnix() --> " + isunix() + nl
see "IsMacOSX() --> " + ismacosx() + nl
see "IsLinux() --> " + islinux() + nl
see "IsFreeBSD() --> " + isfreebsd() + nl
see "IsAndroid() --> " + isandroid() + nl
Output:
IsMSDOS() --> 0
IsWindows() --> 1
IsWindows64() --> 0
IsUnix() --> 0
IsMacOSX() --> 0
IsLinux() --> 0
IsFreeBSD() --> 0
IsAndroid() --> 0
28.8. IsLinux() Function 146

10. Ring Documentation, Release 1.3
28.12 Windowsnl() Function
We can get the windows new line string using the Windowsnl() function.
Syntax:
WindowsNL() ---> Returns a string contains CR+LF = CHAR(13) + CHAR(10)
Example:
cStr = read("input.txt")
if iswindows()
cStr = substr(cStr,windowsnl(),nl)
ok
aList = str2list(cStr)
# to do - list items processing using "for in"
cStr = list2str(aList)
if iswindows()
cStr = substr(cStr,nl,windowsnl())
ok
write("ouput.txt",cStr)
28.13 Get Command Line Arguments
We can get the command line arguments passed to the ring script using the sysargv variable.
The sysargv variable is a list contains the command line parameters.
Example
see copy("=",30) + nl
see "Command Line Parameters" + nl
see "Size : " + len(sysargv) + nl
see sysargv
see copy("=",30) + nl
if len(sysargv) < 4 return ok
nStart = sysargv[3]
nEnd = sysargv[4]
for x = nStart to nEnd
see x + nl
next
Output
b:mahmoudappsring>ring testssyspara.ring 1 10
==============================
Command Line Parameters
Size : 4
ring
testssyspara.ring
1
10
==============================
28.12. Windowsnl() Function 147