int sum(int a, int b){return a + b;
}
int (*p1)(int, int) = sum;
printf("sum = %d\n", p1(2, 3));

typedef void (*Hello)();//注: 新的类型名写在*号后面Hello p3 = hello;p3();typedef int (*Sum)(int, int);Sum p4 = sum;printf("sum = %d\n", p4(2, 4));

int  max(int a, int b){return  a > b ? a : b;
}
int (*p5)(int, int) = max;printf("max = %d\n", p5(3, 4));p5 = sum;printf("sum = %d\n", p5(2, 4));typedef int (*Max) (int, int);Max p6 = max;printf("max = %d\n", p6(7,3));

int sum(int a, int b){return a + b;}int minus(int a, int b){return a - b;}int mul(int a, int b){return a * b;}int divide(int a, int b){return a / b;}int computer(int num1, int num2, int flag){int (*p)(int , int) = NULL;switch (flag) {case 1:p = sum;break;case 2:p = minus;break;case 3:p = mul;break;case 4:p = divide;break;default:break;}return p(num1, num2);
}

  int result = computer(2, 3, 3);

    printf("result = %d\n", result);

int computerPro(int num1, int num2, int (*p)(int, int)){return p(num1, num2);
}result = computerPro(3, 2, min);printf("result = %d\n", result);

struct student{char name[20];int num;int age;
};
typedef struct student Student;void sortArray(Student array[], int count, BOOL (*p)(Student, Student));
BOOL sortByAge (Student stu1, Student stu2);
BOOL sortByNum (Student stu1, Student stu2);
BOOL sortByName(Student stu1, Student stu2);

void sortArray(Student array[], int count, BOOL (*p)(Student, Student)){for (int i = 0; i < count - 1; i++) {for (int j = 0; j < count - 1 - i; j++) {if (p(array[j], array[j + 1])) {Student temp = array[j];//交换结构体变量array[j] = array[j + 1];array[j + 1] = temp;}}}for (int i = 0; i < count; i++) {printf("%s\t %d\t  %d\n", array[i].name, array[i].num, array[i].age);//打印结构体变量
    }}//BOOL(*)(Student, Student)
BOOL sortByAge (Student stu1, Student stu2){return stu1.age >  stu2.age;// BOOL result = stu1.age > stu2.age;return result;
}BOOL sortByNum (Student stu1, Student stu2){return stu1.num >  stu2.num;//2nd
}BOOL sortByName(Student stu1, Student stu2){return strcmp(stu1.name, stu2.name) > 0;
}

Student stu1 = {"zhangsan", 1314, 18};Student stu2 = {"jiujing", 520, 38};Student stu3 = {"laowang", 666, 40};Student stu4 = {"wangmazi", 999, 20};Student stu5 = {"huihui", 1234567, 16};Student array[5] = {stu1, stu2, stu3, stu4, stu5};//冒泡排序//按照年龄从小到大排序sortArray(array, 5, sortByName);