int * p = NULL;p = (int*)malloc(sizeof(int));if (p == NULL){/*...*/}/*初始化為0*/memset(p, 0, sizeof(int));char *ptr = (char *)malloc(10);char name[20] ;memcpy ( name,ptr,20); // Problem begins hereint mark[100]; ...//讓用戶輸入學(xué)生編號，設(shè)現(xiàn)實中學(xué)生編號由1開始：cout << "請輸入學(xué)生編號（在1~100之間）："int i;cin >> i;//輸出對應(yīng)學(xué)生的考試成績：cout << info[i-1];class Object {private:void* data;const int size;const char id;public: Object(int sz, char c):size(sz), id(c){ data = new char[size];cout << "Object() " << id << " size = " << size << endl; } ~Object(){cout << "~Object() " << id << endl;delete []data; }};
void GetMemory2(char **p, int num){ *p = (char *)malloc(sizeof(char) * num);}void Test2(void){ char *str = NULL; GetMemory2(&str, 100); // 注意參數(shù)是 &str，而不是str strcpy(str, "hello"); cout<< str << endl; free(str);}void port();void addr();
int main (){ addr(); port();}long *p ;void port(){ long i, j ; j = 0; for ( i = 0 ; i < 10 ; i++ ) { (*p)--; j++; }}void addr(){ long k; k = 0; p = &k;}char *GetString2(void){ char *p = "hello world"; return p;}void Test5(void){ char *str = NULL; str = GetString2(); cout<< str << endl;}char *p = (char *) malloc(10);strcpy(p, “hello”);free(p); // p所指的內(nèi)存被釋放，但是p所指的地址仍然不變…//忘記 釋放 strcpy(p, “world”); // 出錯char *p = (char *) malloc(10);strcpy(p, “hello”);free(p); // p所指的內(nèi)存被釋放，但是p所指的地址仍然不變…if(p != NULL) // 雖然記得，但沒有起到防錯作用{ strcpy(p, “world”); // 出錯 }
