qsort() 怎么用？

[superwt2001]

MSDN上这么写
void qsort( void *base, size_t num, size_t width, int (__cdecl *compare )(const void *elem1, const void *elem2 ) );
我的是这么用的
typedef struct { char id; int lc, rc; unsigned int lbits, rbits; } RELATION;
RELATION rel[26];
int cmp(RELATION* r1, RELATION* r2) { return (r1->lc - r2->lc); }
qsort(rel, n, sizeof(RELATION), cmp);
不对，编译错误，老是错，改不对
大家帮帮忙

[superwt2001]

谢谢啦，分归你了

[alexlzg]

将cmp定义改为
int cmp(const void *r11, const void *r22)
{
RELATION *r1=(RELATION *)r11;
RELATION *r2=(RELATION *)r22;
return (r1->lc - r2->lc);
}