C++ struct初始化，复制

struct初始化

struct studentInfo
{
	studentInfo():num(123)
	{
		name = "lzc";
	}
	std::string name;
	int num;
};
int main()
{
	studentInfo info;
	std::cout << info.name <<info.num<< std::endl;
    return 0;
}

 

struct可以直接使用=号，或是默认拷贝构造函数赋值

#include "stdafx.h"
#include <stdio.h>
#include <string>
#include <iostream>

struct studentInfo
{
	std::string name;
	int num;
};
int main()
{
	studentInfo info;
	info.name = "lzc";
	info.num = 5;
	//studentInfo info2(info);
	studentInfo info2 = info;
	std::cout << info2.name << " " << info2.num << std::endl;
    return 0;
}

 struct字符数组的赋值：

#include "stdafx.h"
#include <stdio.h>
#include <string>
#include <iostream>
#include <vector>

struct studentInfo
{
	char buf[128];
	int num;
};
int main()
{
	studentInfo info;
	int nSize = sizeof(studentInfo);
	std::cout << "sizeof(studentInfo)=" << nSize << std::endl;
	char* sz = "Hello, World\n";
	strcpy_s(info.buf, sz);
	info.num = 123;
	std::cout << info.buf << info.num << std::endl;
    return 0;
}

struct中char*的赋值

#include "stdafx.h"
#include <stdio.h>
#include <string>
#include <iostream>
#include <vector>

struct studentInfo
{
	char *pSz;
	int num;
};
int main()
{
	studentInfo info;
	int nSize = sizeof(studentInfo);
	std::cout << "sizeof(studentInfo)=" << nSize << std::endl;
	
	char* sz = "Hello, World\n";
	info.pSz = sz;
	info.num = 123;
	std::cout << info.pSz << info.num << std::endl;

	studentInfo info2 = info;
	std::cout << info2.pSz << info2.num << std::endl;
    return 0;
}

struct里的char*如果是new出来的，则在该变量delete之后，调用就会出错，这就是赋值的浅copy，如果要深copy则要将该指针变量也new一遍，并且给这个内存区域赋值，

#include "stdafx.h"
#include <stdio.h>
#include <string>
#include <iostream>
#include <vector>

struct studentInfo
{
	char *pSz;
	int num;
};
int main()
{
	studentInfo info;
	int nSize = sizeof(studentInfo);
	std::cout << "sizeof(studentInfo)=" << nSize << std::endl;
	
	//char* sz = "Hello, World\n";
	char* sz = new char[128];
	sz[0] = 'H';
	sz[1] = 'e';
	sz[2] = 'l';
	sz[3] = 'l';
	sz[4] = 'o';
	sz[5] = 0;
	info.pSz = sz;
	info.num = 123;
	std::cout << info.pSz << info.num << std::endl;
	delete []sz;
	studentInfo info2 = info;
	std::cout << info2.pSz << info2.num << std::endl;
    return 0;
}

struct里面vector等变量可直接赋值

// ConsoleApplication10.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <stdio.h>
#include <string>
#include <iostream>
#include <vector>

struct studentInfo
{
	std::vector<std::string> names;
	int num;
};

void max(int a, int b)
{
	a = 1;
	b = 2;
}

void fn(int& a, int& b)
{
	a = 1;
	b = 2;
}

void test(int* a, int* b)
{
	*a = 8;
	*b = 9;
}
int main()
{
	studentInfo info;
	std::vector<std::string> nameList;
	nameList.push_back("qwe");
	nameList.push_back("980");
	info.names = nameList;
	info.num = nameList.size();
	std::cout << info.num << std::endl;
	for (int i = 0; i < info.num; i++)
	{
		std::cout << info.names[i] << std::endl;
	}

	studentInfo info2(info);
	std::cout << info2.num << std::endl;
	for (int i = 0; i < info2.num; i++)
	{
		std::cout << info2.names[i] << std::endl;
	}

	int num1 = 100;
	int num2 = 200;
	max(num1, num2);
	std::cout << num1 <<","<<num2<< std::endl;

	fn(num1,num2);
	std::cout << num1 << "," << num2 << std::endl;

	test(&num1, &num2);
	std::cout << num1 << "," << num2 << std::endl;
    return 0;
}