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| author | Tobias Klauser <tklauser@distanz.ch> | 2008-01-27 11:37:44 +0100 |
|---|---|---|
| committer | Tobias Klauser <tklauser@xenon.tklauser.home> | 2008-01-27 11:37:44 +0100 |
| commit | 7e0f021a9aec35fd8e6725e87e3313b101d26f5e (patch) | |
| tree | b1cacc4b24393f517aeb4610e9e1021f954307a8 /reference/C/MISC/io.html | |
Initial import (2.0.2-6)2.0.2-6
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| -rw-r--r-- | reference/C/MISC/io.html | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/reference/C/MISC/io.html b/reference/C/MISC/io.html new file mode 100644 index 0000000..356986c --- /dev/null +++ b/reference/C/MISC/io.html @@ -0,0 +1,89 @@ +<title>Input and Output</title> +<body bgcolor="#ffffcc"> +<hr> +<center> +<h1>Input and Output</h1> +</center> +<hr> +<p> +The C language does not have any I/O capability! You can access +files and devices via two groups of functions, these can be split +as shown below.<p> + +<ul> +<li><a href=#low>Low level.</a> +<li><a href=#ansi>ANSI.</a> +</ul> +<a name=low> +<h2>Low Level I/O</h2> + +Low level functions provide direct access to files and devices. If you +only need file read and write you should use the +<a href=#ansi>ANSI</a> functions as your code will remain portable. +If you want to access things like, serial ports, virtual memory and +tape drives, low level I/O is for you.<p> + +Low level functions reference files by a +<a href=../glossary.html#filedes>file descriptor</a>, this descriptor +is created with the <a href=../FUNCTIONS/open.html>open</a> function and +can be referenced by functions like:<p> +<a href=../FUNCTIONS/close.html>close</a><br> +<a href=../FUNCTIONS/read.html>read</a><br> +<a href=../FUNCTIONS/write.html>write</a><br> +mmap - Memory map (Not supported on Linux).<br> +<a href=../MAN/ioctl.htm>ioctl</a> I/O control.<p> + +Three 'file descripters' are opened automatically when your program runs. +These are: +<pre> + File Default + Desc Name device + ---- ---- ------ + 0 <a href=stdfiles.html>stdin</a> Keyboard + 1 <a href=stdfiles.html>stdout</a> Screen + 2 <a href=stdfiles.html>stderr</a> Screen +</pre> + +If you want to use these 'file descriptors', you do not have to issue an +'open'. + + +<a name=ansi> +<h2>ANSI standard functions</h2> + +These functions are defined in the +<a href=../FUNCTIONS/funcref.htm#stdio>stdio.h</a> header. + +The important thing to remember with these functions is the data +is presented in a consistant manor across all platforms. A record +is considered to be 0 or more characters followed by a +<a href=../FUNCTIONS/escape.html>newline</a> character. +If the actual (physical) record is terminated in some other way, the +functions will perform the conversion for you. +<hr> +<p> +<center> +<table border=2 width=80% bgcolor=ivory> +<tr align=center> +<td width=25%> +<a href="../cref.html" target="_top">Top</a> +</td><td width=25%> +<a href="../master_index.html" target="_top">Master Index</a> +</td><td width=25%> +<a href="../SYNTAX/keywords.html" target="_top">C Keywords</a> +</td><td width=25%> +<a href="../FUNCTIONS/funcref.htm" target="_top">Functions</a> +</td> +</tr> +</table> +</center> +<p> +<hr> +<address>Martin Leslie +<script language="JavaScript"> +<!-- // +document.write(document.lastModified); +// --> +</script> +</address> + |