Function prototype: void qsort(void *base, int nelem, int width, int(*fcmp)(const void *, const *))
Header file: #include<stdlib.h>
base: array to be sorted
nelem: length to be sorted
width: size of each array element
cmp: comparison function
Sort of int type
int cmp1(const void *a,const void *b){
//int类型排序 ,从小到大排序
int s1 = *(int *)a;
int s2 = *(int *)b;
if(s1>s2)
return 1;
else if(s1==s2)
return 0;
else
return -1;
}
int main{
int p[10] = {
4,8,9,43,56,83,6,233,4,5};
qsort(p,10,sizeof(int),cmp1); //调用qsort
return 0;
}
Double type sort
int cmp2(const void *a,const void *b){
//double类型排序 ,从小到大排序
double s1 = *(double *)a;
double s2 = *(double *)b;
if(s1>s2)
return 1;
else if(s1==s2)
return 0;
else
return -1;
}
int main{
double d[6] = {
12.1,3.4,33.2,76.5,5.5,7.6};
qsort(d,6,sizeof(double),cmp2); //调用qsort
return 0;
}
char type sort
int cmp3(const void *a,const void *b){
//char类型排序 ,从小到大排序
char s1 = *(char *)a;
char s2 = *(char *)b;
if(s1>s2)
return 1;
else if(s1==s2)
return 0;
else
return -1;
}
int main{
char c[10] = {
'd','a','r','q','p','b','c','x','j','f'};
qsort(c,10,sizeof(c[0]),cmp3); //调用qsort
return 0;
}
String type sort
int cmp4(const void *a,const void *b){
//字符串类型排序 ,从小到大排序 按字典序
char *s1 = (char *)a; //s1,s2用指针
char *s2 = (char *)b;
if(strcmp(s1,s2)>0)
return 1;
else if(strcmp(s1,s2)==0)
return 0;
else
return -1;
}
int main{
char s[6][5] = {
"faf","fdas","ewew","dss","qwer","ffcs"};
qsort(s,6,sizeof(s[0]),cmp4); //调用qsort
return 0;
}
Structure type ordering
struct stu{
char s[10];
int num;
};
int cmp5(const void *a,const void *b){
//对结构体的 s 进行排序 ,从小到大排序
struct stu s1 = *(struct stu *)a;
struct stu s2 = *(struct stu *)b;
if(strcmp(s1.s,s2.s)>0)
return 1;
else if(strcmp(s1.s,s2.s)==0)
return 0;
else
return -1;
}
int main{
struct stu st[4];
strcpy(st[0].s,"张三");
strcpy(st[1].s,"李四");
strcpy(st[2].s,"王五");
strcpy(st[3].s,"大锤");
st[0].num = 43;
st[1].num = 5;
st[2].num = 36;
st[3].num = 3;
qsort(st,4,sizeof(st[0]),cmp5); //调用qsort
return 0;
}