C/C++堆区专篇精讲

#include<iostream>
#include<windows.h>
using namespace std;
int main() {
	int* p = (int*)malloc(20);  //void*  malloc(size) 返回自void指针，参数是字节数
	for (int i = 0; i < 5; i++) {
		p[i] = i;
		//*(p+i) = i;
	}
	cout << p[1] << "  " << *(p + 1) << endl;
	if (p) {
		free(p);  // void free(heap addr)
	}
	system("pause");
	return 0;
}

#include<iostream>
#include<windows.h>
using namespace std;
int main() {
	int* p1 = new int(3);  // 在堆区创建一个int类型数据，并且赋初值
	// int* p2 = new int(0, 1, 2, 3, 4);  // 无法初始化数组
	int* p3 = new int[4];  // 在堆区创建数组，不赋初值
	int(*p4)[3] = new int[2][3];  // 在堆区创建二维数组
	*(p3 + 1) = 1;
	cout << *p1 << endl;
	cout << *(p3 + 1) << endl;
	if (p1) {
		delete p1;
	}
	if (p3) {
		delete[] p3;
	}
	if (p4) {
		delete[] p4;
	}
	system("pause");
	return 0;
}

#include<iostream>
#include<string>
#include<windows.h>
using namespace std;
int main() {
	int num1[5] = { 0, 1, 2, 3, 4 };
	int* p = new int[5];
	memcpy(p, &num1, sizeof(num1));
	cout << *(p + 2) << endl;
	if (p) {
		delete[] p;
	}
	system("pause");
	return 0;
}

#include<iostream>
#include<windows.h>
using namespace std;
int main() {
	int* p = new int[5];
	memset(p, 0, 5 * sizeof(int));  // 将新开辟的的堆区数组设成0
	cout << *(p + 2) << endl;
	if (p) {
		delete[] p;
	}
	system("pause");
	return 0;
}