gmclee@21cn.com wrote:
Hi there,
I need a program to extract a substring from the following pattern

xxxx<XXXXX>xxxx

therer, x and X are any character and the string between < and is
what I need. I use the following program to extract the substring, but
something wrong

char* deangle(const char* lpStr)
{
char *lpBuf = (char *)lpStr;
char *p = strchr( lpBuf, '<' ) + 1;
if (!p) return NULL;
char *q = strchr( lpBuf, '>' );
if (!q) return NULL;
*q = '\0'; /* to make sure no extra characters at the end of the
substring
memcpy( lpBuf, p, q-p );
return lpBuf;
}

In addition to the various points made so far you also have a big
logic error. What does deangle do when passed a string of the form
"xxx>XXXX<xxx"?

So as not to be accused of being too negative, I would propose:

char *deangle(char *str)
{
char *open = strchr(str, '<');
if (!open)
return NULL;
char *close = strchr(open + 1, '>');
if (!close)
return NULL;
int sublen = (close - open) - 1; /* will be >= 0 */
memmove(str, open + 1, sublen);
str[sublen] = '\0';
return str;
}

or, in older C, and in the single-entry-exit style:

char *deangle(char *str)
{
char *close;
char *open = strchr(str, '<');
if (open && (close = strchr(open + 1, '>'))) {
int sublen = (close - open) - 1; /* will be >= 0 */
memmove(str, open + 1, sublen);
str[sublen] = '\0';
}
else str = NULL;
return str;
}

but I would argue against the idea of returning a pointer to the same
(clobbered) data. What if the string has two <parts and you
later want both?