C第12章-----堆

#include <stdio.h>

#include <stdlib.h>

//声明Person结构

//struct Person{

// float heightInMeters;

// int weightInKilos;

//};

//声明Person类型

typedef struct{

float heightInMeters;

int weightInKilos;

}Person;

//float bodyMassIndex(Person p){

// return p.weightInKilos / (p.heightInMeters * p.heightInMeters);

//}

float bodyMassIndex(Person *p){

return p->weightInKilos / (p->heightInMeters * p->heightInMeters);

}

int main(int argc, const char * argv[]) {

//使用malloc()函数可以得到一块内存缓冲区，当程序不在使用这块缓冲区时，可以调用free()函数，释放相应的内存，将其返回给堆。

//使用sizeof()来获得缓冲区的准确大小。

//为一个Person结构分配内存

Person *mikey = (Person *)malloc(sizeof(Person));

//为一个Person结构分配内存

mikey->weightInKilos = 96;

mikey->heightInMeters = 1.7;

//计算并输出BMI

float mikeyBMI = bodyMassIndex(mikey);

printf("mikey has a BMI of %f ", mikeyBMI);

//释放占用的内存，使之能够被重用

free(mikey);

//将指针变量赋为空

mikey = NULL;

return 0;

// //struct Person mikey;

// //Person mikey;

// mikey.heightInMeters = 1.7;

// mikey.weightInKilos = 96;

// //struct Person aaron;

// //Person aaron;

// aaron.heightInMeters = 1.97;

// aaron.weightInKilos = 84;

// printf("mikey is %.2f meters tall. ", mikey.heightInMeters);

// printf("mikey weights %d kilograms. ", mikey.weightInKilos);

// printf("aaron is %.2f meters tall. ", aaron.heightInMeters);

// printf("aaron weights %d kilograms. ", aaron.weightInKilos);

// float bmi;

// bmi = bodyMassIndex(mikey);

// printf("mikey has a BMI of %.2f ", bmi);

// bmi = bodyMassIndex(aaron);

// printf("aaron has a BMI of %.2f ", bmi);

// return 0;

}