Comment on trim string function please

[DiAvOl]

My implementation of a trim function (It may contain bugs but it works
for me):

char *trim(char *str) {
int len;
while(isspace(*str))
str++;
len = strlen(str);

while(isspace(*(str+(--len))))
;

str[++len] = '\0';

return str;
}

 

[Ian Collins]

DiAvOl said:


Given an empty string, this function attempts to access the character that
comes *before* the start of the string. That's a showstopper.

Not to mention what happens with a NULL string...

 

[Ben Bacarisse]

DiAvOl said:


You'll need <ctype.h> for this - and note that the behaviour is undefined
if a negative value is encountered before the first whitespace character
(on systems where char is signed).




Given an empty string, this function attempts to access the character that
comes *before* the start of the string. That's a showstopper.

Or any string consisting of only space characters (which includes, in
some sense, the empty string).