const操作符

(1)、int* const p;

const修飾p，表示p不能被修改；指針常量，const int a;

(2)、const int *p、int const *p;

const 修飾*p， *p不能被修改(即不能通過指針間接修改它“指向”的數據)；常量指針->指向常量的指針。

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示例

    char a = 'q';
    char b = 'o';
    char* const pp = &b; //p:指針常量,const修飾p，p不能被修改
    //p = &a; //error

    int aa = 1;
    int bb = 2;
    int const *ppp = &aa;//*ppp不能被修改 ppp:常量指針
    aa = 10;
    //*ppp = 20; //error，不能通過pp間接對它指向的數據進行修改
    ppp = &bb;

    const int* pppp = &aa;
    //*pppp = 20; //error
    pppp = &bb;

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