C语言指针

i=3;
*i_pointer=3;

int *p1;

int *p2;    //p2是指向整型变量的指针变量
float *p3;  //p3是指向浮点变量的指针变量
char *p4;   //p4是指向字符变量的指针变量

#include <stdio.h>
int main(){
    int *p;
    printf("%X\n", p);  //十六进制输出
    return 0;
}

int a=10;
int *p=&a;

int a=10;
int *p;
p=&a;

int *p;
p=1000;

int i=200, x;
int *ip;

ip=&i;

x = *ip;

x = i;

int i, j, *p1, *p2;
i = ‘a‘;
j = ‘b‘;
p1 = &i;
p2 = &j;

*p2=*p1;

int x, y, *px = &x;

y=*px+5;  //表示把x的内容加5并赋给y
y=++*px;  //px的内容加上1之后赋给y，++*px相当于++(*px)
y=*px++;  //相当于y=*px; px++

#include <stdio.h>
int main(){
    int a=100, b=10;
    int *pointer_1, *pointer_2;
    pointer_1 = &a;
    pointer_2 = &b;
    printf("%d, %d\n", a, b);
    printf("%d, %d\n", *pointer_1, *pointer_2);
    return 0;
}

#include <stdio.h>
int main(){
    int *max, *min,*tmp, a, b;
    scanf("%d, %d",&a, &b);
    max = &a;
    min = &b;
    if(*max < *min){
        // 交换指针变量的值，tmp 为临时变量
        tmp = max;
        max = min;
        min = tmp;
    }
    printf("a=%d, b=%d\n", a, b);
    printf("max=%d, min=%d\n", *max, *min);
    return 0;
}

#include <stdio.h>
// 交换两个数
void swap(int *p1, int *p2){
    int temp;  //临时变量
    temp = *p1;
    *p1 = *p2;
    *p2 = temp;
}
int main(){
    int a, b;
    int *pointer_1, *pointer_2;
    scanf("%d, %d",&a, &b);
    pointer_1 = &a;
    pointer_2 = &b;
    if(a<b){
        swap(pointer_1, pointer_2);
    }
    printf("\n%d, %d\n",a, b);
    return 0;
}

void swap(int *p1,int *p2){
    int *temp;
    *temp=*p1;  //此语句有问题
    *p1=*p2;
    *p2=temp;
}

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

#include <stdio.h>
// 交换两个数
void swap(int *p1,int *p2){
    int *p;
    p = p1;
    p1 = p2;
    p2 = p;
}
int main(){
    int a, b;
    int *pointer_1, *pointer_2;
    scanf("%d, %d",&a, &b);
    pointer_1 = &a;
    pointer_2 = &b;
    if(a<b){
        swap(pointer_1, pointer_2);
    }
    printf("\n%d, %d\n",a, b);
    return 0;
}

#include <stdio.h>
int main(){
    int a=5;
    int *p=&a;
    printf("%d\n", *p);
    return 0;
}

int a, *pa;
pa=&a;  //把整型变量a的地址赋予整型指针变量pa

int a[5], *pa;
pa=a;  //数组名表示数组的首地址，可以赋予指向数组的指针变量pa

pa=&a[0];  //数组第一个元素的地址也是整个数组的首地址，也可赋予pa

int a[5], *pa=a;

char *pc;
pc="C Language";

char *pc="C Language";

int (*pf)();
pf = func;  //func 为函数名

int a[5],*pa;
pa=a;  //pa指向数组a，也是指向a[0]
pa=pa+2;  //pa指向a[2]，即pa的值为&pa[2]

#define NULL 0
int *p = NULL;

#include <stdio.h>
int main(){
    //pa、pb为整型指针变量
    int a=10, b=20, sum, product, *pa, *pb;
    pa = &a;  //给指针变量pa赋值，pa指向变量a
    pb = &b;  //给指针变量pb赋值，pb指向变量b
    sum = *pa + *pb;  //求a+b之和，*pa就是a，*pb就是b
    product = *pa * *pb;  //本行是求a*b之积
    printf("a=%d\nb=%d\na+b=%d\na*b=%d\n", a, b, a+b, a*b);
    printf("s=%d\nt=%d\n", sum, product);
    return 0;
}

int a[10];  //定义a为包含10个整型数据的数组
int *p;  //定义p为指向整型变量的指针

p=&a[0];

p=&a[0];
p=a;

int *p=&a[0];

int *p;
p=&a[0];

int *p=a;

#include <stdio.h>
int main(){
    int a[10], i;
    for(i=0; i<10; i++)
        a[i]=i;
    for(i=0;i<10;i++)
        printf("a[%d]=%d\n", i, a[i]);
    return 0;
}

#include <stdio.h>
int main(){
    int a[10], i;
    for(i=0; i<10; i++)
        *(a+i) = i;
    for(i=0; i<10; i++)
        printf("a[%d]=%d\n", i, *(a+i));
    return 0;
}

#include <stdio.h>
int main(){
    int a[10], i, *p;
    p = a;
    for(i=0; i<10; i++)
        *(p+i) = i;
    for(i=0; i<10; i++)
        printf("a[%d]=%d\n", i, *(p+i));
    return 0;
}

#include <stdio.h>
int main(){
    int *p, i, a[10];
    p=a;
    for(i=0; i<10; i++)
        *p++=i;
    for(i=0; i<10; i++)
        printf("a[%d]=%d\n", i, *p++);
    return 0;
}

#include <stdio.h>
int main(){
    int *p, i, a[10];
    p=a;
    for(i=0; i<10; i++)
        *p++=i;
    p=a;
    for(i=0; i<10; i++)
        printf("a[%d]=%d\n", i, *p++);
    return 0;
}

#include <stdio.h>
float aver(float a[5]){
    int i;
    float average, sum=a[0];
    for(i=1; i<5; i++)
        sum += a[i];
    average = sum/5;
    return average;
}
int main(){
    float scores[5], average;
    int i;
    printf("Input 5 scores:\n");
    for(i=0; i<5; i++)
        scanf("%f", &scores[i]);
    average = aver(scores);
    printf("Average score is %5.2f", average);
    return 0;
}

#include <stdio.h>
void nzp(int *a){
    int i;
    for(i=0; i<5; i++){
        if(a[i]<0) a[i]=0;  //小于0的元素，赋值为0
    }
}
int main(){
    int b[5], i;
    printf("Input 5 numbers:\n");
    for(i=0; i<5; i++)
        scanf("%d", &b[i]);
    printf("Initial values of array b are: ");
    for(i=0; i<5; i++)
        printf("%d ", b[i]);
    nzp(b);
    printf("\nFinal values of array b are: ");
    for(i=0; i<5; i++)
        printf("%d ",b[i]);
    return 0;
}

void nzp(int a[])

void nzp(int *a)

#include <stdio.h>
int main(){
    char string[] = "I love China!";
    printf("%s\n", string);
    return 0;
}

#include <stdio.h>
int main(){
    char *string = "I love China!";
    printf("%s\n", string);
    return 0;
}

char c, *p=&c;

char *s="C Language";

char *string = "I love China!";

char *string;
string = "I love China!";

#include <stdio.h>
int main(){
    char *ps = "This is a good tutorial!";
    int n=10;
    ps=ps+n;
    printf("%s\n", ps);
    return 0;
}

#include <stdio.h>
int main(){
    char str[20], *ps;
    int i;
    printf("Input a string: ");
    ps = str;
    scanf("%s", ps);
    for(i=0; ps[i]!=‘\0‘; i++){
        if(ps[i]==‘k‘){
            printf("There is a ‘k‘ in the string!\n");
            break;
        }
    }
 
    if(ps[i]==‘\0‘) printf("There is no ‘k‘ in the string\n");
    return 0;
}

#include <stdio.h>
void cpystr(char *pss, char *pds){
    while((*pds=*pss)!=‘\0‘){
        pds++;
        pss++;
    }
}
int main(){
    char *pa = "Apple, Samsung, Xiaomi, Smartisan", b[100], *pb;
    pb=b;
    cpystr(pa, pb);
    printf("string a=%s\nstring b=%s\n",pa, pb);
    return 0;
}

void cprstr(char *pss,char*pds){
    while( (*pds++=*pss++) != ‘\0‘ );
}

void cprstr(char *pss,char*pds){
    while(*pds++ = *pss++);
}

#include <stdio.h>
// 返回两个字符串中较长的一个
char *func(char *str1, char *str2){
    if(strlen(str1) >= strlen(str2)){
        return str1;
    }else{
        return str2;
    }
}
int main(){
    char *s1 = "C Language";
    char *s2 = "C is very great!";
    char *longstr = func(s1, s2);
    printf("Long string: %s\n", longstr);
    return 0;
}

数据类型 (*指针变量名)();

#include <stdio.h>
// 返回两个值中较大的值
int max(int a, int b){
    if(a>b) return a;
    else return b;
}
int main(){
    int(*pmax)();
    int x, y, maxval;
    pmax = max;
    printf("Input two numbers:");
    scanf("%d %d", &x, &y);
    maxval = (*pmax)(x, y);
    printf("Max value: %d\n", maxval);
    return 0;
}

0   1   2   3
4   5   6   7
8   9  10  11

int a[3][4]={{0,1,2,3},{4,5,6,7},{8,9,10,11}};

#include <stdio.h>
int main(){
    int a[3][4]={0,1,2,3,4,5,6,7,8,9,10,11};
    printf("  a=%d,",a);
    printf("     *a=%d,",*a);
    printf(" a[0]=%d,",a[0]);
    printf(" &a[0]=%d,",&a[0]);
    printf(" &a[0][0]=%d\n",&a[0][0]);
    printf("a+1=%d,",a+1);
    printf(" *(a+1)=%d,",*(a+1));
    printf(" a[1]=%d,",a[1]);
    printf(" &a[1]=%d,",&a[1]);
    printf(" &a[1][0]=%d\n",&a[1][0]);
    printf("a+2=%d,",a+2);
    printf(" *(a+2)=%d,",*(a+2));
    printf(" a[2]=%d,",a[2]);
    printf(" &a[2]=%d,",&a[2]);
    printf(" &a[2][0]=%d\n\n",&a[2][0]);
    printf("   a[1]+1=%-8d,",a[1]+1);
    printf("    *(a+1)+1=%-8d\n",*(a+1)+1);
    printf("*(a[1]+1)=%-8d,",*(a[1]+1));
    printf(" *(*(a+1)+1)=%-8d\n",*(*(a+1)+1));
    return 0;
}

数据类型 *数组名[数组长度];

int *pa[3] = { a[0], a[1], a[2] };

#include <stdio.h>
int main(){
    int a[3][4] = {0,1,2,3,4,5,6,7,8,9,10,11};
    int *pa[3]={a[0], a[1], a[2]};  //也可以不指定长度，写作 int*pa[]
    int *p=a[0];  //整型指针
    printf("%d, %d, %d\n", a[1][2], *a[1], *(*(a+1)+2));
    printf("%d, %d, %d\n", *pa[1], p[2], *(p+2));
    return 0;
}

int (*p)[4];

数据类型  (*指针变量名)[长度];

#include <stdio.h>
int main(){
    int a[3][4]={0,1,2,3,4,5,6,7,8,9,10,11};
    int(*p)[4];
    int i,j;
    p=a;
    for(i=0; i<3; i++){
        for(j=0; j<4; j++) printf("%2d  ",*(*(p+i)+j));
        printf("\n");
    }
    return 0;
}

p=&a;  //将变量a的地址赋给p
p=array;  //将数组array的首地址赋给p
p=&array[i];  //将数组array第i个元素的地址赋给p
p=max;  //max为已定义的函数，将max的入口地址赋给p
p1=p2;  //p1和p2都是指针变量，将p2的值赋给p1