A question related to strcmp

Here is a program I wrote to construct a suffix array.

Code:

int pstrcmp(const void* str1, const void* str2){
	int tmp = strcmp((char*)str1, (char*)str2);
	return tmp;
}

int main(){

	char str[]="to be or not to be this is a problem.";
	char **a = (char**) malloc(sizeof(char*)*strlen(str));

	for(int i=0;i<strlen(str);i++){
		a[i] = &str[i];
	}

	qsort(a,strlen(str),sizeof(char*),pstrcmp);
	for(int i=0;i<strlen(str);i++) cout<<a[i]<<endl;

        return 0;
}

It seems pstrcmp doesn't work.... When I debug the pstrcmp, the tmp value is always -1! Anybody knows what's wrong?

Hold on, did you intend to post this in the C programming forum?

EDIT:
oops, sorry. I didnt look carefully. It does look like it was written to be a C program at a glance

FYI: Array A contains address of the following strings.

to be or not to be this is a problem.
o be or not to be this is a problem.
be or not to be this is a problem.
be or not to be this is a problem.
e or not to be this is a problem.
or not to be this is a problem.
or not to be this is a problem.
r not to be this is a problem.
not to be this is a problem.
not to be this is a problem.
ot to be this is a problem.
t to be this is a problem.
to be this is a problem.
to be this is a problem.
o be this is a problem.
be this is a problem.
be this is a problem.
e this is a problem.
this is a problem.
this is a problem.
his is a problem.
is is a problem.
s is a problem.
is a problem.
is a problem.
s a problem.
a problem.
a problem.
problem.
problem.
roblem.
oblem.
blem.
lem.
em.
m.
.

Consider the string "abracadabra", of length 11. It has eleven suffixes: "abracadabra", "bracadabra", "racadabra", and so on down to "a". Sorted into lexicographical order, these suffixes are

a
abra
abracadabra
acadabra
adabra
bra
bracadabra
cadabra
dabra
ra
racadabra

Your cast inside the compare function is wrong.

*(char**)str1

Thank you! It works. But I still don't understand why is this. Each element in array A is char*, isn't it?

Originally Posted by Salem

Your cast inside the compare function is wrong.

*(char**)str1

If each element of your array is a 'T', then the qsort compare function receives two 'T*' pointers.