int maxValue(int x,int y)
{
return x > y ? x : y;
}
void printHello()
{
printf("hello\n");
}
int max(int x,int y)
{
return x < y ? x : y;
}
int sum(int x,int y)
{
return x + y;
}
int getValue(int x,int y,int (*p)(int ,int ))
{
// p是函数指针,具体指向一个函数,由调用函数时传入的函数名决定
int r = p(x,y);
return r;
}
int main(int argc, const char * argv[]) {
#pragma mark --------------------函数指针--------------------
/*
函数: 实现某种特定功能的代码
程序编译时,系统会将函数代码分配在代码区,这段存储空间的起始地址就是函数的地址.又称
函数的指针
函数名和数字名一样是地址
// 通过函数名调用函数
printf("%d ",maxValue(3,5));
函数指针: 指向函数的指针.可以通过函数指针调用指向的函数
定义函数指针指向maxValue函数
指针类型必须与指向的数据的类型匹配,函数有类型,函数指针必须和函数的类型保持一致
maxValue函数的类型 int(int,int)
返回值类型 (*函数指针名)(参数类型) = 函数名
int (*p)(int x,int y) = maxValue;
printf("%d ",p(30,50));
// 函数指针类型:返回值类型 (*)(参数类型) 例如:
int (*)(int x ,int y);
// 练习: void printHello(); 定义一个可以指向上述函数的函数指针,并通过函数指针实现调用该函数
void (*p)() = printHello;
p();
// 练习 定义两个函数,?一个求最?大值,?一个求和,输?入max或sum分别求3,5的 最?大值或和(提?示,定义?一个函数指针,根据输?入内容指向不同函数,最后 ?一次调?用完成)
char a[5] = {0};
scanf("%s",a);
if (strcmp(a, "sum") == 0)
{
int (*p)(int x,int y) = sum;
printf("%d ",p(3,5));
}
if (strcmp(a, "max") == 0)
{
int (*p)(int x,int y) = max;
printf("%d ",p(3,5));
}
printf("\n");
*/
#pragma mark --------------回调函数------------------
/*
//函数指针作为函数参数
int (*p)(int ,int ) = max;
int (*q)(int ,int ) = sum;
int max1 = getValue(3, 5, p);
int sum2 = getValue(3, 5, q);
printf("%d %d\n",max1,sum2);
回调过程: 在getValue执行的过程中,体内各国传入的函数指针,调用执行某个函数
回调函数: 在函数执行过程中.通过函数指针被调用的函数
函数回调: 调用回调函数的操作
*/
// 练习 写?一函数查找成绩90分以上的学员,使?回调函数在姓名后加”?富帅”。
/*
Student stu1[3] =
{
{1,"zhangsan",84.0},
{2,"lisi",59.0},
{3,"wangwu",96.0}
};
Student *p = stu1;
findstudentScorechengji(p);
*/
/*
Student stu1 = {"wukong", ‘m‘, 500, 60.0};
Student stu2 = {"zixia", ‘w‘, 18, 98.0};
Student stu3 = {"sanzang", ‘w‘, 40, 100.0};
Student stu4 = {"longma", ‘w‘, 27, 93.0};
Student stu5 = {"bajie", ‘w‘, 300, 59.0};
Student stus[5] = {stu1, stu2, stu3, stu4, stu5};
// 定义一个函数指针，指向拼接字符串函数
void (*p)(char*) = addStr;
findStudentByScore(stus, 5, p);
printAllStudent(stus, 5);
*/
#pragma mark ----------动态排序--------------
// 排序: 排序的规则不同,年龄,姓名,成绩,升序,降序
//利用回调函数实现动态排序
Student stu1 = {"wukong", ‘m‘, 500, 60.0};
Student stu2 = {"zixia", ‘w‘, 18, 98.0};
Student stu3 = {"sanzang", ‘w‘, 40, 100.0};
Student stu4 = {"longma", ‘w‘, 27, 93.0};
Student stu5 = {"bajie", ‘w‘, 300, 59.0};
Student stus[5] = {stu1, stu2, stu3, stu4, stu5};
// printf("按姓名排序\n");
// sortStudentByName(stus,5);
// AllStudent(stus,5);
// printf("按分数排序\n");
// sortStudentByScore(stus,5);
// AllStudent(stus,5);
// printf("按年龄排序\n");
// sortStudentByAge(stus,5);
// AllStudent(stus,5);
//
printf("新玩法\n");
// printf("按姓名排序\n");
// sortStudent(stus,5,compartStudentByName);
// AllStudent(stus,5);
// printf("按分数排序\n");
// sortStudent(stus,5,compartStudentByScore);
// AllStudent(stus,5);
// printf("按年龄排序\n");
// sortStudent(stus,5,compartStudentByNAge);
// AllStudent(stus,5);
#pragma mark ------------函数的返回值是函数的指针--------------
m.h
typedef struct
{
char name[30];
char sex;
int age;
float score;
}Student;
void findstudentScorechengji(Student *p);
// 根据名字大小排序
void sortStudentByName(Student *stus,int count);
//根据分数排
void sortStudentByScore(Student *stus,int count);
//根据年龄排
void sortStudentByAge(Student *stus,int count);
//遍历输出
void AllStudent(Student *stus,int count);
// 新玩法
typedef BOOL (*SORT)(Student,Student);
//SORT代表的是一个类型函数指针,指向的函数的返回值是BOOL类型,参数是俩个Student变量
//实现排序函数
void sortStudent(Student *stus,int count,SORT p_sort);
BOOL compartStudentByName(Student stu1,Student stu2);
BOOL compartStudentByScore(Student stu1,Student stu2);
BOOL compartStudentByNAge(Student stu1,Student stu2);
m.m
/*
void findstudentScorechengji(Student *p)
{
for (int i = 0; i < 3; i ++)
{
if ((p + i) -> score > 90)
{
strcat((p + i) -> name, "高富帅");
printf("%d %s %.1f\n",(p + i) -> num,(p+i) -> name,(p + i) -> score);
}
}
}
*/
/*
void findStudentByScore(Student *stus,int count,void (*p)(char *)){
for (int i = 0; i < count;i++) {
if (stus[i].score > 90) {
p(stus[i].name);//函数回调
}
}
}
void printAllStudent(Student *stus,int count){
for (int i = 0; i < count; i++) {
printf("name = %s, sex = %c, age = %d, score = %.2f\n",stus[i].name,stus[i].sex,stus[i].age,stus[i].score);
}
}
*/
// 根据名字大小排序
void sortStudentByName(Student *stus,int count)
{
for (int i = 0; i < count - 1; i ++)
{
for (int j = 0; j < count - 1 - i; j ++)
{
if (strcmp(stus[j].name,stus[j+1].name ))
{
Student temp = stus[j];
stus[j] = stus[j + 1];
stus[j + 1] = temp;
}
}
}
}
//根据分数排
void sortStudentByScore(Student *stus,int count)
{
for (int i = 0; i < count - 1; i ++)
{
for (int j = 0; j < count - 1 - i; j ++)
{
if (stus[j].score > stus[j+1].score)
{
Student temp = stus[j];
stus[j] = stus[j + 1];
stus[j + 1] = temp;
}
}
}
}
//根据年龄排
void sortStudentByAge(Student *stus,int count)
{
for (int i = 0; i < count - 1; i ++)
{
for (int j = 0; j < count - 1 - i; j ++)
{
if (stus[j].age > stus[j+1].age)
{
Student temp = stus[j];
stus[j] = stus[j + 1];
stus[j + 1] = temp;
}
}
}
}
//遍历输出
void AllStudent(Student *stus,int count)
{
for (int i = 0; i < count; i++) {
printf("name:%s sex:%c age:%d score:%.1f\n",stus[i].name,stus[i].sex,stus[i].age,stus[i].score);
}
}
//实现排序函数
void sortStudent(Student *stus,int count,SORT p_sort)
{
for (int i = 0; i < count - 1; i ++)
{
for (int j = 0; j < count -i - 1; j ++)
{
if (p_sort(stus[j],stus[j+1]))
{
Student temp = stus[j];
stus[j] = stus[j+1];
stus[j+1] = temp;
}
}
}
}
BOOL compartStudentByName(Student stu1,Student stu2)
{
return strcmp(stu1.name, stu2.name) > 0;
}
BOOL compartStudentByScore(Student stu1,Student stu2)
{
return stu1.score > stu2.score;
}
BOOL compartStudentByNAge(Student stu1,Student stu2)
{
return stu1.age > stu2.age;
}