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进阶指针_wx630c8eb20b5ff的技术博客_51CTO博客
source link: https://blog.51cto.com/u_15770447/5754919
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进阶指针_wx630c8eb20b5ff的技术博客_51CTO博客
p指向的arr的首地址，%s打印字符串，遇到‘\0’停止，两者打印效果相同。
int main()
{
char arr[] = "abcdef";
char* p = arr;
printf("%s\n", arr);
printf("%s\n", p);
return 0;
}
{
char arr[] = "abcdef";
char* p = arr;
printf("%s\n", arr);
printf("%s\n", p);
return 0;
}
const char* p="abcdef";
常量字符串，p存的是首字符。*p不能够被更改。
const char* p1 = "abcdef";
const char* p2 = "abcdef";
const char* p2 = "abcdef";
p1和p2存储的字符串相等，所以用的一份空间。
p1改变时，p2不会应为p1改变而改变。
!!指针数组!!
指针数组是数组
int arr[] = { 0 };//整形数组
int ch[] = { 0 };//字符数组
int* parr[2];//存放指针的数组
char* pch[2];//存放指针的数组
int ch[] = { 0 };//字符数组
int* parr[2];//存放指针的数组
char* pch[2];//存放指针的数组
数组从0开始计数，
int main()
{
int arr1[] = { 1,2,3 };
int arr2[] = { 3,4,5 };
int i;
int* a [] = {arr1,arr2};
for (i = 0; i < 2; i++)
{
int j;
for (j = 0; j < 3; j++)
{
printf("%d", a[i][j]);//打印所有数
}
printf("\n");
}
return 0;
}
{
int arr1[] = { 1,2,3 };
int arr2[] = { 3,4,5 };
int i;
int* a [] = {arr1,arr2};
for (i = 0; i < 2; i++)
{
int j;
for (j = 0; j < 3; j++)
{
printf("%d", a[i][j]);//打印所有数
}
printf("\n");
}
return 0;
}
!!数组指针!!
数组指针是指针。
//[]优于*
int arr[3] = { 1,2,3 };
int(*p)[3] = &arr;//数组地址存起来
int arr[3] = { 1,2,3 };
int(*p)[3] = &arr;//数组地址存起来
void print(int(*p)[2], int x, int y)
{
int i;
for (i = 0; i < x; i++)
{
int j;
for (j = 0; j < y; j++)
{
printf("%d", *(*(p + i)+j));//*(p + i)跳过i行
printf("%d", (*(p + i)[j]));//三者相等
printf("%d", (p [i][j]));
}
printf("\n");
}
}
int main()
{
int arr[3][2] = {1,2,3,4,5,6};
print(arr, 3, 2);
return 0;
}
{
int i;
for (i = 0; i < x; i++)
{
int j;
for (j = 0; j < y; j++)
{
printf("%d", *(*(p + i)+j));//*(p + i)跳过i行
printf("%d", (*(p + i)[j]));//三者相等
printf("%d", (p [i][j]));
}
printf("\n");
}
}
int main()
{
int arr[3][2] = {1,2,3,4,5,6};
print(arr, 3, 2);
return 0;
}
数组传参，指针传参
一维数组传参
void test1(int arr[10])//可以去掉数字或者用*arr代替
{}
void test2(int* arr[20])//可用int**arr代替，可以去数字
}
int main()
{
int arr1[10] = { 0 };
int*arr2[20] = { 0 };
test1(arr1);
test2(arr2);
return 0;
}
{}
void test2(int* arr[20])//可用int**arr代替，可以去数字
}
int main()
{
int arr1[10] = { 0 };
int*arr2[20] = { 0 };
test1(arr1);
test2(arr2);
return 0;
}
二维数组传参
void test1(int arr[][5])//可以去掉数字，用*arr代替
{}
void test1(int(*arr)[5])
{}
int main()
{
int arr1[3][5];//3可以不写
test1(arr1);
return 0;
}
{}
void test1(int(*arr)[5])
{}
int main()
{
int arr1[3][5];//3可以不写
test1(arr1);
return 0;
}
二级指针传参
void test1(int**p)
{}
int main()
{
int n;
int* p = &n;
int** pp = &p;
test1(pp);
test1(&p);
return 0;
}
{}
int main()
{
int n;
int* p = &n;
int** pp = &p;
test1(pp);
test1(&p);
return 0;
}
函数有地址
printf（“%p”，&add）；//add可以去&
(*(void(*)())0)()
*(void(*)()指针函数，（)0，强制转换0的地址为指针函数，最后调用地址为0的函数。
void(*signal(int ,void(*)(int)))(int);
typedef void(*fu)(int);//简化
fu signal(int, fu);
fu signal(int, fu);
数组指针运用
int add(int x, int y)
{
return x + y;
}
int main()
{
int (*pa)(int,int) = add;
printf("%d", (*pa)(2,3));
return 0;
}
{
return x + y;
}
int main()
{
int (*pa)(int,int) = add;
printf("%d", (*pa)(2,3));
return 0;
}
函数指针的数组
int add(int x, int y)
{
return x + y;
}
int did(int x, int y)
{
return x - y;
}
int mul(int x, int y)
{
return x * y;
}
int div(int x, int y)
{
return x / y;
}
int main()
{
int (*pa)(int,int) = add;
int(*parr[4])(int, int) = { add,did,mul,div };
int i;
for (i = 0; i < 4; i++)
{
printf("%d\n", parr[i](2, 3));
}
return 0;
}
{
return x + y;
}
int did(int x, int y)
{
return x - y;
}
int mul(int x, int y)
{
return x * y;
}
int div(int x, int y)
{
return x / y;
}
int main()
{
int (*pa)(int,int) = add;
int(*parr[4])(int, int) = { add,did,mul,div };
int i;
for (i = 0; i < 4; i++)
{
printf("%d\n", parr[i](2, 3));
}
return 0;
}
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