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code question# Programming - 葵花宝典

t*n2008-03-05 08:03

1 楼

the sample from programming pearls. But, I got complier error at this line
qsort(a, n, sizeof(char *), pstrcmp). How can I fix this one? Thanx.
#include
#include
#include
int pstrcmp(char **p, char **q)
{ return strcmp(*p, *q); }
#define MAXN 5000000
char c[MAXN], *a[MAXN];
int main()
{ int i, ch, n = 0, maxi, maxlen = -1;
while ((ch = getchar()) != EOF) {
a[n] = &c[n];
c[n++] = ch;
}

c[n] = 0;
qsort(a, n, sizeof(char *), pstrcmp);
}

P*e2008-03-05 08:03

2 楼

int pstrcmp(const void *p, const void *q)
{ return strcmp((char*)p, (char*)q); }
google qsort

【在 t*********n 的大作中提到】

: the sample from programming pearls. But, I got complier error at this line
: qsort(a, n, sizeof(char *), pstrcmp). How can I fix this one? Thanx.
: #include
: #include
: #include
: int pstrcmp(char **p, char **q)
: { return strcmp(*p, *q); }
: #define MAXN 5000000
: char c[MAXN], *a[MAXN];
: int main()

r*r2008-03-05 08:03

3 楼

the new c compiler is stricter on type checking.
the last argument to qsort function is of type:
int ( * comparator ) ( const void *, const void * )
therefore, you need to cast the pstrcmp to this type. do:
typedef int(*cmp_ptr) (const void *, const void *);
qsort(a, n, sizeof(char *), (cmp_ptr) pstrcmp);

t*n2008-03-05 08:03

4 楼

many thanks. it works.

【在 r*********r 的大作中提到】

: the new c compiler is stricter on type checking.
: the last argument to qsort function is of type:
: int ( * comparator ) ( const void *, const void * )
: therefore, you need to cast the pstrcmp to this type. do:
: typedef int(*cmp_ptr) (const void *, const void *);
: qsort(a, n, sizeof(char *), (cmp_ptr) pstrcmp);