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  • c语言指针

    C语言用三种方式打印数组

    #include<stdio.h>
void pointarray2(int a[]){//用指针变量指向数组元素
	int *point;
	int i;
	for(i=0;i<10;i++){
		point=&a[i];
		printf("%d",*point);
	}
	printf("
");
}
void pointarray(int a[]){//通过数组名计算数组的元素地址,找出元素的值
	int *point;
	int i;
	point=a;
	for(i=0;i<10;i++){
		printf("%d",*(point+i));
	}
	printf("
");
}

int main(){
	int a[10]={9,8,7,6,5,4,3,2,1,0};
	int i;
	for(i=0;i<10;i++){//下标法
		printf("%d",a[i]);
	}
	printf("
");
	pointarray(a);
	pointarray2(a);
	return 0;
}

    实现数组倒序存储

    #include<stdio.h>
void swap(int *p1,int *p2){
	int temp;
	temp=*p1;
	*p1=*p2;
	*p2=temp;
}
void reverse(int a[],int n){
	int i;
	int *low,*high;
	for(i=0;i<=(n-1)/2;i++){
		low=&a[i];
		high=&a[n-1-i];//n-1-i指向对应的元素
		swap(low,high);
	}
}

int main(){
	int a[10]={3,4,6,2,3,1,4,5,6,0};
	int n=10,i;
	for(i=0;i<n;i++){
		printf("%d",a[i]);
	}
	printf("
");
	printf("reverse later---------
");
	reverse(a,10);//将数组倒叙排放
	for(i=0;i<n;i++){
		printf("%d",a[i]);
	}
	printf("
");
}

    max min search

    #include<stdio.h>
int *max,*min;
void Max_Min_Search(int *a,int n){
	int i=0;
	max=a;
	min=a;
	for(;i<n;i++){
		if(a[i]>*max){
			max=&a[i];
		}
		if(a[i]<*min){
			min=&a[i];
		}
	}
}
int main(){
	int a[10]={24,10,23,5,2,540,26,30,34,35};

	int i=0;
	for(;i<10;i++){
		printf("%d ",a[i]);
	}

	printf("
");
	printf("---------------Searching------------------
");
	Max_Min_Search(a,10);
	printf("max=%d min=%d
",*max,*min);
}

    image-20191024163739066

    打印二维数组

    #include<stdio.h>

void PrintTwoArray(int (*a)[4],int row,int len){//(*a)[4]必须要传递列值,数组指针变量
	int i,j;
	for(i=0;i<row;i++){
		for(j=0;j<len;j++){
			printf("%d ",*(*(a+i)+j));
		}
		printf("
");
	}
}

int main(){
	int a[3][4]={5,6,7,8,9,3,0,4,5,6,7,3};
	printf("a的地址:%d
",a);
	printf("a: %d
",&a);
	printf("a[0]:%d
",a[0]);
	printf("*(*(a+1)):%d
",*(*(a+1)));
	printf("*(*(a+1)+2):%d
",*(*(a+1)+2));
	printf("&a[1][0]:%d
",&a[1][0]);
	printf("--------------------
");
	PrintTwoArray(a,3,4);
}

    copy字符串

    #include<stdio.h>


void print_string(char *string){
	printf("----------------string b is------
");
	for(;*string!='';string++){
		printf("%c",*string);
	}
	printf("
");
}
void copy_string5(char *a,char *b){
	char *p;
	p=b;
	while(*p++=*a++){}
	p=b;
	print_string(p);
}


void copy_string4(char *a,char *b){
	char *p;
	p=b;
	while(*a!=''){
		*p++=*a++;
	}
	p=b;
	print_string(p);
}

void copy_string3(char *a,char *b){
	char *p;
	p=b;
	while((*p++=*a++)!=''){
	}
	p=b;
	print_string(p);
}
void copy_string2(char *a,char *b){
	char *p;
	p=b;
	while((*p=*a)!=''){
		p++;
		a++;
	}
	p=b;
	print_string(p);

}
void copy_string1(char *a,char *b){
	char *p1,*p2;
	p2=b;
	p1=a;
	for(;*p1!='';p1++,p2++){
		*p2=*p1;
	}
	*p2='';
	p2=b;
	printf("-------------------------
");
	print_string(p2);
}
int main(){
	char string[]="hello world";
	char *a="i love you",b[]="hello world ",*p1,*p2;//此处应该定义为char b[] 而不能用char  *b;因为char *b放在了常量区,不能被修改.
	char *s="hello ";
	int i;
	printf("%s
",string);
	printf("%s
",s);
	
	p1=a;
	p2=b;
	for(;*p1!='';p1++,p2++){
		*p2=*p1;
	}
	*p2='';
	printf("----------------string b is-------
");
	for(i=0;b[i]!='';i++){
		printf("%c",b[i]);
	}
	printf("---------------------
");
	copy_string1(a,b);	
	copy_string2(a,b);
	copy_string3(a,b);
	copy_string4(a,b);
	copy_string5(a,b);

}

    image-20191025192914077

    image-20191025200423203

    image-20191025200537661

    image-20191025200650572

    image-20191025201016685

    指针函数传递参数

    #include<stdio.h>

int add(int x,int y){
	return x+y;
}
int min(int x,int y){
	if(x>y){
		return y;
	}
	return x;
}
int max(int x,int y){
	if(x>y){
		return x;
	}else{
		return y;
	}
}
void prosess(int x,int y,int (*fun)()){///////////////////
	printf("%d
",fun(x,y));
}
int main(){
	int min(int,int);
	int max(int,int);
	int add(int,int);
	void prosess(int ,int ,int (*fun)());

	int a,b;
	scanf("%d %d",&a,&b);
	printf("max=");
	prosess(a,b,max);
	printf("min=");
	prosess(a,b,min);
	printf("sum=");
	prosess(a,b,add);
}

    输入序号打印学生各科成绩

    #include<stdio.h>
int *search(int (*score)[4],int id){
	return *(score+id);
}
int main(){
	int score[][4]={12,3,34,54,56,25,63,90,12,57,63,27};
	int id,i;
	int *p;
	scanf("%d",&id);
	if(id-1>0&&id-1<3){
		p=search(score,id-1);
		for(i=0;i<4;i++){
			printf("%d ",*(p+i));
		}
		printf("
");
	}

}

    判断不及格的学生

    #include<stdio.h>
int *search(int (*score)[4],int id){
	return *(score+id);
}

int print_score1(int (*score)[4],int i){
	int j;
		for(j=0;j<4;j++){
			if(*(*(score+i)+j)<60){
				return i+1;
			}
		}
		return -1;
	}

void print_score(int *p){
	int i=0;
	for(;i<4;i++){
		printf("%d ",*(p+i));
	}
	printf("
");
}

int main(){
	int score[][4]={12,3,34,54,70,89,63,90,12,57,63,27};
	int id,i;
	int *p1;
	scanf("%d",&id);
	if(id-1>=0&&id-1<3){
		p1=search(score,id-1);
		print_score(p1);
	}
	for(i=0;i<3;i++){
		if(print_score1(score,i)>0){
			printf("%d号不及格 ",print_score1(score,i));
		}else{
			printf("及格 ");
		}
	}
}

    image-20191026001020291

    字符串排序

    #include<stdio.h>
#include<string.h>
void sort(char *name[],int n){
	int i,j;
	char *p;
	for(i=0;i<n-1;i++){
		for(j=i+1;j<n;j++){
			if(strcmp(name[i],name[j])>0){
				p=name[i];
				name[i]=name[j];
				name[j]=p;
			}
		}
	}
}
void print(char *name[] , int n){
	int i;
	for(i=0;i<n;i++){
		printf("%s ",name[i]);
	}
	printf("
");
}
int main(){//指针数组
	char *name[]={"php","go","c++","java","c"};

	int n=5;
	sort(name,n);
	print(name,n);
	
}

    image-20191026004814972

    	char *name[]={"php","go","c++","java","c"};
	char **p;
	int i;
	int n=5;
	for(i=0;i<n;i++){
		p=name+i;
		printf("%5s",*p);
	}

    image-20191026005311004

    image-20191026005650753

    image-20191026010454116

    image-20191026010537453

    image-20191026010620952

    void test(){
	int name[]={1,2,4,53,3};
	int *p1,*p2;
	p1=&name[1];
	p2=&name[4];
	printf("%d",p2-p1);//3
}

    image-20191026011538963

    image-20191026011736366

    image-20191026011836077

    带参数的宏定义

    image-20191027135958486

    image-20191027140124000

    #include<stdio.h>

#define M(a,b) (a>b)?a:b

int main(){
	int a,b;
	scanf("%d %d",&a,&b);
	printf("max=%d",M(a,b));
}

    image-20191027140729793

    image-20191027140848028

    image-20191027141110205

    image-20191027141521576

    image-20191027142416728

    image-20191027142443507

    image-20191027143938237

    结构体

    image-20191027144701230

    image-20191027150035130

    #include<stdio.h>
struct date{
	int year;
	int month;
	int day;
};
struct{
	int id;
	char *name;
	char gender;
	int age;
	float score;
	char *addr;
	struct date birthday;
}student1,student2={1,"hanmeimei",'m',45,22.2f,"hubei",2019,12,12};

int main(){
	student1=student2;
	printf("number=%d
name=%s
gender=%c
age=%d
score=%f
addr=%s
birthday=%d-%d-%d
",student1.id,student1.name,student1.gender,student1.age,student1.score,student1.addr,student1.birthday.year,student1.birthday.month,student1.birthday.day);

}

    实现投票

    #include<stdio.h>
#include<string.h>
struct PushTicket{
		char *name;
		int ticket;
	}*point,ticket[5]={{"hanmeimei",0},{"lilei",0},{"lili",0},{"c",0},{"java",0}};
	
void PrintTicket(struct PushTicket *point){
	int i;
	point=ticket;
	printf("------------候选人的票-----------
");
	for(i=0;i<5;i++,point++){
		printf("%s-----:%d
",point->name,point->ticket);
	}
			
}
void compare(char *input){
	int i;
	point=ticket;
	for(i=0;i<5;i++,point++){
		if(strcmp(input,point->name)==0){
			(point->ticket)++;
		}
	}
}
int main(){
	int i;
	char input[20];
	point=ticket;
	printf("------------候选人-----------
");
	for(i=0;i<5;i++,point++){
		printf("%s ",point->name);
	}
	printf("
");
	printf("---------------
");
	while(1){
		printf("请输入候选人名称投票:");
		scanf("%s",&input);
		compare(input);
		if(strcmp(input,"-1")==0){
			break;
		}


	}
			PrintTicket(point);
}

    动态数组

    image-20191027183935021

    image-20191027184043371

    image-20191027184110721

    image-20191027184156656

    链表

    #include<stdio.h>
struct student{
	int num;
	float score;
	struct student *next;
};
void PrintLink(struct student *p){
	while(p!=NULL){
		printf("num=%d,score=%f",p->num,p->score);
		p=p->next;
	}
	
}
int main(){
	struct student a,b,c,*head;
	a.num=1;
	a.score=89.0f;
	a.next=&b;
	b.num=2;
	b.score=90;
	b.next=&c;
	c.num=3;
	c.score=100;
	c.next=NULL;
	head=&a;
	PrintLink(head);
}

    image-20191027223049024

    #include<stdio.h>
#include<malloc.h>

#define LEN sizeof(struct student)
struct student{//定义链表
	int num;
	float score;
	struct student *next;
};
void print(struct student *head){//打印链表
	while(head!=NULL){
		printf("num=%d,score=%f
",head->num,head->score);
		head=head->next;
	}
}
struct student *DeleteNode(int input,struct student *head){
	struct student *p1,*p2;
	if(head==NULL){
		printf("空链表
");
	}	
	p1=head;	
		while(p1->num!=input&&p1->next!=NULL){//当输入的shu和链表的书不相等时.
			p2=p1;
			p1=p1->next;
		}
		if(p1->num==input){
			if(p1==head){
				head=p1->next;	
			}else{
				p2->next=p1->next;
			}
		}
		return head;
	}
struct student *insert(struct student *stu,struct student *head){//有bug
	struct student *p1,*p2,*p0;
	p0=stu;
	if(head==NULL){
		printf("NUll linktable
");
	}
	p1=head;
	while(p0->num>p1->num&&(p1->next!=NULL)){
		p2=p1;
		p1=p1->next;
		if(p0->num<=p1->num){
			if(head==p1){
				head=p0;
			}else{
				p2->next=p0;
				p0->next=p1;
			}

		}else{
			p1->next=p0;
			p0->next=NULL;
		}

	}
	p1=head;
	p2=p1;
return head;


}
struct student *create(){//创建链表
	int n=0;
	struct student *head,*p1,*p2;
	p1=p2=(struct student *)malloc(LEN);
	printf("input num-------------:");
	scanf("%d",&p1->num);
	printf("input score-----------:");
	scanf("%f",&p1->score);
	head=NULL;
	while(p1->num!=0){
		n++;
		if(n==1){
			head=p1;
		}else{
			p2->next=p1;
		}
		
	
		p2=p1;
		p1=(struct student *)malloc(LEN);
		printf("input num-------------:");
		scanf("%d",&p1->num);
		printf("input score-----------:");
		scanf("%f",&p1->score);
	}
		p2->next=NULL;

	return head;
	
}
int main(){
	int input;
	struct student *stu,*p,stu1;
	stu=create();
	p=stu;
	print(p);
	printf("
");
	printf("删除节点-----:");
	scanf("%d",&input);
	print(DeleteNode(input,p));
	printf("
");
	printf("插入节点");
	printf("input num-------------:");
	scanf("%d",&stu1.num);
	printf("input score-----------:");
	scanf("%f",&stu1.score);
	print(insert(&stu1,stu));
	printf("
");


printf("插入节点");
	printf("input num-------------:");
	scanf("%d",&stu1.num);
	printf("input score-----------:");
	scanf("%f",&stu1.score);
	print(insert(&stu1,stu));
	printf("
");

}

    image-20191028182743903

    #include<stdio.h>
#include<stdlib.h>

int main(){
	FILE *file;
	if(!(file=fopen("d:\hello.txt","w"))){
		printf("error");
	}else{
		printf("success!!!
");
		
	}
}

    image-20191029131827023

    image-20191029142743283

    image-20191029144251829

    image-20191029144350161

    image-20191029144636084

    image-20191029144811799

    image-20191029144847446

    用位运算实现大小写转换

    #include<stdio.h>


int main(){
	char ch;
	printf("please input char:");
	ch=getchar();
	while(!(ch>'A'&&ch<'z')||(ch>'Z'&&ch<'a')){
		printf("error please input:
");
		ch=getchar();
	}
	if(ch & 32){//32的二进制位是100000 ch&100000得到第五位数是0,然后就换转大写
		ch=ch&223;
	}else{
	
		ch=ch|255;//得到第五位数是1 转小写.
	}
	putchar(ch);

	ch=getchar();//打印回车
	putchar(ch);


}

    image-20191029151159306

    image-20191029151309955

    image-20191029151500290

    image-20191029151813040

    image-20191029152251623

    image-20191029152632086

    image-20191029152726176

    image-20191029153550877

    struct与malloc

    #include<stdio.h>
#include<malloc.h>
#define LEN sizeof(struct student)
struct student{
	int id;
	char *name;
	int score;
};

void fun(struct student *p){
	(*p).id=12;
	p->name="hello";
	p->score=90;

}
void show(struct student *p){
	printf("%d %s %d
",p->id,p->name,p->score);
}

int main(){
	struct student *stu;
	stu=(struct student *)malloc(LEN);
	fun(stu);
	//printf("%d %s %d",stu.id,stu.name,stu.score);
	show(stu);
}

    动态数组的增删排

    #include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
struct Arr{
	int *pBase;//数组的首地址
	int len;//数组的长度
	int cnt;//当前有效元素的个数
};


void init_arr(struct Arr *,int length);

int append_arr(struct Arr *,int val);//追加

int insert_arr(struct Arr *,int pos,int val);

int delete_arr(struct Arr *,int pos,int *val);

//int get();

int is_empty(struct Arr *p);

int is_full(struct Arr *p);

int sort_arr(struct Arr *p);

void show_arr(struct Arr *p);

int reverse_arr(struct Arr *p);

int main(){
	struct Arr arr;
	int val;
	init_arr(&arr,6);
	append_arr(&arr,100);
	append_arr(&arr,99);
	append_arr(&arr,80);
	append_arr(&arr,23);
	if(append_arr(&arr,45)){
		printf("append success
");
	}
	insert_arr(&arr,7,555);
	if(append_arr(&arr,567)){
		printf("append success
");
	}

	if(append_arr(&arr,1000)==1){
		printf("append success
");
	}
	printf("%d
",arr.cnt);
	show_arr(&arr);
	printf("----------删除元素-------
");
	delete_arr(&arr,3,&val);
	printf("--------删除的元素是:%d
",val);
	show_arr(&arr);
	printf("----------倒置元素--------
");
	reverse_arr(&arr);
	show_arr(&arr);
	printf("----------排序-------------
");
	sort_arr(&arr);
	show_arr(&arr);
	printf("%d
",arr.cnt);
	

}
void init_arr(struct Arr *p,int length){
	p->pBase=(int *)malloc(sizeof(int)*length);
	if(NULL==p->pBase){
		printf("error
");
		exit(-1);
	}
	p->len=length;
	p->cnt=0;

	return;
}
int is_empty(struct Arr *p){
	if(p->cnt==0){
		return 1;
	}
	return 0;

}
void show_arr(struct Arr *p){
	int i;
	if(is_empty(p)==1){
		printf("数组为空
");	
	}
	for(i=0;i<p->cnt;i++){
		printf("%d ",*(p->pBase+i));
	}
	printf("
");
}

int is_full(struct Arr *p){
	if(p->cnt==p->len){
		return 1;
	}
	return 0;
}
int  append_arr(struct Arr *p,int val){
	if(is_full(p)==1){
		printf("数组已满
");
		return 0;
	}
	//不满时
	p->pBase[p->cnt]=val;
	(p->cnt)++;
	return 1;
}
int insert_arr(struct Arr *p,int pos,int val){
	int i=(p->cnt)-1;
	if(pos<1||pos>(p->cnt)+1){//<1或者大于当前有效元素
		return 0;
	}
	if(is_full(p)==1){
		printf("数组已满
");
		return 0;
	}
	//pos的值从1开始,且从pos的位置之前插入
	for(;i>=pos-1;i--){
		p->pBase[i+1]=p->pBase[i];
	}
	p->pBase[pos-1]=val;
	(p->cnt)++;
	return 1;

}
int delete_arr(struct Arr *p,int pos,int *val){
	int i;
	if(is_empty(p)==1){
		printf("数组为空
");
		return 0;
	}
	if(pos<1||pos>p->cnt){
		return 0;
	}
	*val=p->pBase[pos-1];
	for(i=pos;i<=p->cnt;i++){
		p->pBase[i-1]=p->pBase[i];
	}
	(p->cnt)--;
	return 1;
}
int reverse_arr(struct Arr *p){
	int i=0,temp,j=p->cnt-1;
	//int *low,*high;
	if(is_empty(p)==1){
		printf("数组为空
");
		return 0;
	}
	while(i<j){
		temp=p->pBase[i];
		p->pBase[i]=p->pBase[j];
		p->pBase[j]=temp;
		i++;
		j--;
	}
	
	/*low=&(p->pBase[0]);
	high=&(p->pBase[p->cnt]);
	for(i=0;i<=(high-low)/4;i++){
		low=&(p->pBase[i]);
		high=&(p->pBase[p->cnt-1-i]);
		temp=*low;
		*low=*high;
		*high=temp;
	}*/
	return 1;

}
int sort_arr(struct Arr *p){
	int i,min,j,temp;
	for(j=0;j<p->cnt;j++){
		min=p->pBase[j];
		for(i=j+1;i<p->cnt;i++){
			if(p->pBase[i]<min){
				temp=p->pBase[i];
				p->pBase[i]=min;
				min=temp;
			}
		}
			p->pBase[j]=min;
	}

	return 1;
}

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  • 原文地址：https://www.cnblogs.com/321915514wx/p/philxling.html
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