From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/c/io%2Fsetbuf.html | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 devdocs/c/io%2Fsetbuf.html (limited to 'devdocs/c/io%2Fsetbuf.html') diff --git a/devdocs/c/io%2Fsetbuf.html b/devdocs/c/io%2Fsetbuf.html new file mode 100644 index 00000000..fb5c4a93 --- /dev/null +++ b/devdocs/c/io%2Fsetbuf.html @@ -0,0 +1,46 @@ +

setbuf

Defined in header <stdio.h> 
void setbuf( FILE          *stream, char          *buffer );
+		 (until C99) 
void setbuf( FILE *restrict stream, char *restrict buffer );
+		 (since C99) 
#define BUFSIZ     /*unspecified*/
+

Sets the internal buffer to use for stream operations. It should be at least BUFSIZ characters long.

+

If buffer is not null, equivalent to setvbuf(stream, buffer, _IOFBF, BUFSIZ).

+

If buffer is null, equivalent to setvbuf(stream, NULL, _IONBF, 0), which turns off buffering.

+

Parameters

+ + +
stream - the file stream to set the buffer to
buffer - pointer to a buffer for the stream to use. If a null pointer is supplied, the buffering is turned off

Return value

None.

+

Notes

If BUFSIZ is not the appropriate buffer size, setvbuf can be used to change it.

+

setvbuf should also be used to detect errors, since setbuf does not indicate success or failure.

+

This function may only be used after stream has been associated with an open file, but before any other operation (other than a failed call to setbuf/setvbuf).

+

A common error is setting the buffer of stdin or stdout to an array whose lifetime ends before the program terminates:

+
int main(void) {
+    char buf[BUFSIZ];
+    setbuf(stdin, buf);
+} // lifetime of buf ends, undefined behavior

Example

+

setbuf may be used to disable buffering on streams that require immediate output.

+
#include <stdio.h>
+#include <threads.h>
+ 
+int main(void)
+{
+    setbuf(stdout, NULL); // unbuffered stdout
+    putchar('a'); // 'a' appears immediately if stdout is unbuffered
+    thrd_sleep(&(struct timespec){.tv_sec=1}, NULL); // sleep 1 sec
+    putchar('b'); 
+}

Output:

+
ab

References

See also

+ +
sets the buffer and its size for a file stream
(function)
C++ documentation for setbuf
+

+ © cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
+ https://en.cppreference.com/w/c/io/setbuf +

+
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