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Top Forums Programming How i use pointer as a string in c programing? Post 302708325 by Corona688 on Monday 1st of October 2012 11:29:50 AM
Old 10-01-2012
Quote:
Originally Posted by raihan004
but without declaring arry its work on windows how and why?
By complete coincidence, nothing more. If this was a debug build, a release build might crash, or vice versa. You are using undefined behavior -- undefined doesn't mean "will crash", undefined means "unpredictable".

Windows will let you get away with very stupid things -- temporarily. It allowed me to delete my video surface sixty times per second and not crash then and there. It still crashed, but far later, in mysterious ways which took days to debug, because not crashing immediately meant I had no clue where the bug was.

Using undefined memory means you're wrecking something, somewhere. You might be overwriting your stack pointer, wrecking your ability to make function calls. You might be overwriting something in heap space, ruining heap pointers and causing weird malloc() crashes later. You might be in data space and overwriting your global variables. This is not safe, stable, or sane. Memory does not work that way. Use a buffer.

Last edited by Corona688; 10-01-2012 at 12:39 PM..
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index(3C)						   Standard C Library Functions 						 index(3C)

NAME
index, rindex - string operations SYNOPSIS
#include <strings.h> char *index(const char *s, int c); char *rindex(const char *s, int c); DESCRIPTION
The index() and rindex() functions operate on null-terminated strings. The index() function returns a pointer to the first occurrence of character c in string s. The rindex() function returns a pointer to the last occurrence of character c in string s. Both index() and rindex() return a null pointer if c does not occur in the string. The null character terminating a string is considered to be part of the string. USAGE
On most modern computer systems, you can not use a null pointer to indicate a null string. A null pointer is an error and results in an abort of the program. If you wish to indicate a null string, you must use a pointer that points to an explicit null string. On some machines and with some implementations of the C programming language, a null pointer, if dereferenced, would yield a null string. Though often used, this practice is not always portable. Programmers using a null pointer to represent an empty string should be aware of this portability issue. Even on machines where dereferencing a null pointer does not cause an abort of the program, it does not necessarily yield a null string. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
bstring(3C), malloc(3C), string(3C), attributes(5), standards(5) SunOS 5.10 24 Jul 2002 index(3C)
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