C及数据结构一瞥_艾孜尔江撰_struct.person.name

#include<iostream>
using namespace std;

void run();

int main() {
	run();
}

void run() {

	//int i2 = 555, i1 = 666; //if opened, the result will be 1, which is the space not allocated
	int i1= 555 , i2 = 666; //跟声明顺序有关，先声明的变量会先被分配到内存空间
	int* ptr = &i1;

	cout << &i1 << " : " << &i2 << endl;

	ptr--;
	int i3 = *ptr;
	cout << i3 << endl;//666
}

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#include <stdio.h>

int main(int argc, char *argv[]) {
	
//	// Uncleaned
//	// 下面申请的20个字节的内存有可能被别人用过
//	char chs[20];
//	// 这个代码打印出来的可能就是乱码，因为printf的%s是“打印一直遇到'\0'”。
//	printf("%s\n",chs);



	// Cleaned!
	int i;
	char chs[20] = { 0 };
	for(i=0; i<sizeof(chs)/sizeof(char); i++) {
		printf("%d | ",chs[i]);
	}
	printf("\n");
	int nums[10] = { 7, 5 };
	for(i=0; i<sizeof(nums)/sizeof(int); i++) {
		printf("%d | ",nums[i]);
	}
	return 0;
}
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#include<stdio.h>

int main(){
	int nums[] = {3,5,6,7,9};
    void* ptr1 = nums;
    //int i = *ptr1; // 对于void指针没法直接取值
    int* ptr2 = (int*)nums;
    printf("%d,%d\n",ptr1,ptr2);
    int i = *ptr2;
    printf("%d\n",i);
}
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#include<stdio.h>
#include<string.h>

struct _Person
{
    char *name; 
    int age; 
    double height; 
};

int main(int argc, char *argv[])
{
    struct _Person p1;
    // 不初始化内存区域是脏的
    printf("Dirty --- p1.age is %d\n",p1.age);
    
    // 方法一：使用memset进行清理
    memset(&p1,0,sizeof(struct _Person));
    printf("Cleaned in Way1 --- p1.age is %d\n",p1.age);
    p1.name = "Alexander";
    p1.age = 25;
    printf("Cleaned in Way1 --- Name : %s , Age : %d\n",p1.name,p1.age);
    printf("Cleaned in Way1 --- p1.age is %d\n",p1.age);
    printf("------------------------------\n");
    
    // 方法二：初始化
    struct _Person p2 = { 0 };
    p2.name = "刘德华";
    p2.age = 60;
    printf("Cleaned in Way2 --- Name : %s , Age : %d\n",p2.name,p2.age);
    return 0;
}
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#include<stdio.h>

typedef void (*intFunc)(int i); // Function pointer 



void test1(int age) {
	printf("test1:%d\n\n",age);
}

void foreachNums(int *nums,int len,intFunc func) {
	int i;
	for(i=0; i<len; i++) {
		int num = nums[i];
		func(num); // call the function through its pointer
	}
}

void printNum(int num) {
	printf("value=%d\n",num);
}

int main() {
	// 声明一个intFunc类型的函数指针
	intFunc f1 = test1;
	// 执行f1函数指针所指向的代码区
	f1(8);

	int nums[] = { 1,5,666,23423,223 };
	foreachNums(nums,sizeof(nums)/sizeof(int),printNum); // send the function as pointer
}
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#include<stdio.h>
#include<stdlib.h>


///Initial one using stack
//int *getData()
//{
//    int nums[10]={1,2,3,4,5,6,7,8};
//    return nums;
//}
// 
//int *getData2()
//{
//    int aaa[10]={8,7,6,5,4,3,2,1};
//    return aaa;
//}
//
//int main(int argc, char *argv[])
//{
//    int *nums = getData();
//    getData2(); // open and close
//    printf("%d,%d,%d\n",nums[0],nums[1],nums[2]);
//
//    return 0;
//}







///Developed one using heap
int *getData()
{
    int *nums = (int*)malloc(sizeof(int)*10);
    nums[0]=1;
    nums[1]=8;
    nums[2]=3;

    return nums;
}

int *getData2()
{
    int *nums = (int*)malloc(sizeof(int)*10);
    nums[0]=2;
    nums[1]=7;
    nums[2]=5;

    return nums;
}

int main(int argc, char *argv[])
{
    int *numsptr = getData();
    int *numsptr2 = getData2();
    // numptr[1]等价于*(numptr+1)
    printf("%d,%d,%d\n",numsptr[0],numsptr[1],numsptr[2]);
    // 不要忘记释放内存
    free(numsptr);
    free(numsptr2);

    return 0;
}
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#include<stdio.h>

void mymemset(void *data,int num,int byteSize)
{
    // char就是一个字节，而计算机中是以字节为单位存储的
    char *ptr = (char*)data;
    int i;
    for(i=0;i<byteSize;i++)
    {
        *ptr=num;
        ptr++;
    }
}

int main(int argc, char *argv[])
{
    int nums[20];
    mymemset(nums,0,sizeof(nums));
    int i,len=sizeof(nums)/sizeof(int);
    for(i=0;i<len;i++)
    {
        printf("%d ",nums[i]);
    }
    printf("\n");

    return 0;
}
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#include<stdio.h>


// 分解一个三位数，传递个位、十位和百位数字
int parseNumber(int num,int* g,int* s,int* b)
{
    if(num < 100 || num > 999)
    {
        // 只允许100~999的数字
        return -1;
    }

    *g = num % 10;
    *s = (num / 10)%10;
    *b = (num/100)%10;

    return 1;
}


int main(int argc, char *argv[])
{
    int num = 365;
    int g,s,b;
    if(parseNumber(num,&g,&s,&b))
    {
        printf("%d %d %d\n",b,s,g); //3  6  5 
    }
    return 0;            
} 


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#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
//#define LOCAL
int d[101][101];
int a[101][101];
int n;
int dp(int x, int y) {
	if(d[x][y] >= 0) {
		return d[x][y];
	}
	return d[x][y] = a[x][y] + (x == n? 0: max(dp(x + 1, y), dp(x + 1, y + 1)));
}
int main() {
	#ifdef LOCAL
	FILE *fi;
	fi = fopen("hdu2084.txt", "r");
	#endif
	/*
	int c;
	scanf("%d", &c);
	while(c--) {
		int a[101][101];
		memset(a, 0, sizeof(a));
		int n;
		scanf("%d", &n);
		for(int i = 1; i <= n; i++) {
			for(int j = 1; j <= i; j++) {
				scanf("%d", &a[i][j]);
			}
		}
		for(int j = 1; j <= n; j++) {
			d[n][j] = a[n][j];
		}
		for(int i = n - 1; i >= 1; i--) {
			for(int j = 1; j <= i; j++) {
				d[i][j] = a[i][j] + max(d[i + 1][j], d[i + 1][j + 1]);
			}
		}
		printf("%d\n", d[1][1]);
	}
	*/
	int c; 
	scanf("%d", &c);
	while(c--) {
		memset(d, -1, sizeof(d));
		scanf("%d", &n);
		for(int i = 1; i <= n; i++) {
			for(int j = 1; j <= i; j++) {
				scanf("%d", &a[i][j]);
			}
		}
		for(int j = 1; j <= n; j++) {
			d[n][j] = a[n][j];
		}     
		dp(1, 1);
		printf("%d\n", d[1][1]);
	}
	return 0;
}

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#include<iostream>
using namespace std;



void SwapWayOne(int* x, int* y) {
	int temp = 0;
	temp = *x;
	*x = *y;
	*y = temp;
}



void SwapWayTwo(int &x, int &y) {
	int temp = 0;
	temp = x;
	x = y;
	y = temp;
}


void failedSwapWay(int x, int y) {
	int temp = 0;
	temp = x;
	x = y;
	y = temp;
}




inline void inlineSwapWayOne(int* x, int* y) {

	//address of x: 0x6ffde0, address of y: 0x6ffde8
	cout << "address of x: " << &x << ", " << "address of y: " << &y << endl;
	//value of address x: 0x6ffe0c, value of address y: 0x6ffe08
	cout << "value of address x: " << *(&x) << ", " << "value of address y: " << *(&y) << endl;
	//value of address x: 0x6ffe0c, value of address y: 0x6ffe08
	cout << "value of address x: " << x << ", " << "value of address y: " << y << endl;
	//value of x: 5, value of y: 9
	cout << "value of x: " << *x << ", " << "value of y: " << *y << endl;

	int temp = 0;
	temp = *x;
	*x = *y;
	*y = temp;
}



inline void inlineSwapWayTwo(int &x, int &y) {

	//address of x: 0x6ffe0c, address of y: 0x6ffe08
	cout << "address of x: " << &x << ", " << "address of y: " << &y << endl;
	//value of x: 5, value of y: 9
	cout << "value of x: " << *(&x) << ", " << "value of y: " << *(&y) << endl;
	//value of x: 5, value of y: 9
	cout << "value of x: " << x << ", " << "value of y: " << y << endl;

	int temp = 0;
	temp = x;
	x = y;
	y = temp;
}



inline void failedSwapThoughInline(int x, int y) {
	int temp = 0;
	temp = x;
	x = y;
	y = temp;
}


int main() {
	int numA = 5, numB = 9;
	cout << "Original order: " << numA << ", " << numB << endl;

//	failedSwapWay(numA, numB);
//	SwapWayOne(&numA, &numB);
//	SwapWayTwo(numA, numB);
//	inlineSwapWayOne(&numA, &numB);
	inlineSwapWayTwo(numA, numB);
//	failedSwapThoughInline(numA,numB); // inline function's scope is still inside!

	cout << "After changed: " << numA << ", " << numB <<endl;

	return 0;
}
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#include <iostream>
using namespace std;

class Student {
	public:
		Student(char *name, int age, float score);
	public:
		friend void show(Student *pstu);  //将show()声明为友元函数
	private:
		char *m_name;
		int m_age;
		float m_score;
};

Student::Student(char *name, int age, float score): m_name(name), m_age(age), m_score(score) { }

//非成员函数
void show(Student *pstu) {
	cout<<pstu->m_name<<"的年龄是 "<<pstu->m_age<<"，成绩是 "<<pstu->m_score<<endl;
}

int main() {
	Student stu("小明", 15, 90.6);
	show(&stu);  //调用友元函数
	Student *pstu = new Student("李磊", 16, 80.5);
	show(pstu);  //调用友元函数

	return 0;
}

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