What is the meaning of the char * const * type in C language?

Question:

char* – pointer to a variable of type char.

char* const – a constant pointer.

const char* – pointer to a constant variable.

const char* const – a constant pointer to a constant.

char const* is the same as const char* . It is automatically converted to it.

But the gcc(c99) compiler talks about char* const* as a separate type. Same with const char* const* . What is the meaning of * after const together with char* ? How to describe this type?

Answer:

This is the same pointer to pointer as char** , but you cannot change its address (of the pointer to which the variable points).

    char* pc1 = (char*)malloc(LENGTH); strcpy(pc1, "Hello");
    char* pc2 = (char*)malloc(LENGTH); strcpy(pc2, "World");

    char* const* ppc1 = &pc1; // OK
    *ppc1 = pc2; // compile-time error

    char** ppc2 = &pc1; // OK
    *ppc2 = pc2; // OK
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