[c++基础] const char and static const char

部分内容摘自：https://blog.csdn.net/ranhui_xia/article/details/32696669

The version with const char * will copy data from a read-only location to a variable on the stack.

The version with static const char * references the data in the read-only location (no copy is performed).

在函数内部，const char *每次调用函数时，都需要在stack上分配内存，然后将数据拷贝过来，函数退出前释放。

而static const char *，会直接访问read only的数据，无需再stack上分配内存。

char * const cp : 定义一个指向字符的指针常数，即const指针

const char* p : 定义一个指向字符常数的指针

char const* p : 等同于const char* p

举个例子：

 1 #include <iostream>
 2 #include <cstdio>
 3 using namespace std;
 4 
 5 int main()
 6 {
 7     char ch[3] = {'a','b','c'};
 8     char* const cp = ch;
 9     printf("char* const cp: \n %c\n", *cp);
10     /* 
11     ** cp point to a fixed address
12     **
13     cp++;  //error: increment of read-only variable ‘cp’
14     printf("char* const cp: \n %c\n", *cp);
15     **
16     */
17 
18     const char ca = 'a';
19     const char* p1 = &ca;
20 
21     /* 
22     ** 2. Only const char* pointer can point to a const char
23     **
24     const char cb = 'b';
25     char* p2 = &cb; //error: invalid conversion from ‘const char*’ to ‘char*’
26     **
27     **/
28 
29     /*
30     ** 3. p1 points to a const char, the char be pointed has to be const, 
31     **    p1 can point to a different const char
32     */ 
33     printf("const char* p1: \n %c\n", *p1);
34     const char cb = 'b';
35     p1 = &cb;
36     printf(" %c\n", *p1);
37     return 0;
38 }
39 
40 /*
41 ** Output:
42 char* const cp: 
43  a
44 const char* p1: 
45  a
46  b
47 **
48 */