c++ - Printf - 访问冲突读取位置 - C++

Question

0xC0000005: Access violation reading location 0xcccccccc.

printf 抛出这个异常。

我不知道为什么会这样...这些字符串变量中有值。我用错了 printf 吗？

帮助! (请看开关盒)

string header;
string body;
string key;

if (!contactList.isEmpty()) {

    cout << "Enter contact's name: ";
    getline(cin, key);
    Contact * tempContact = contactList.get(key);
    if (tempContact != NULL) {
        string name = tempContact->getName();
        string number = tempContact->getNumber();
        string email = tempContact->getEmail();
        string address = tempContact->getAddress();

        //I've just put this here just to test if the variables are being initialized
        cout << name + " " + number + " " + email + " " + address << endl;

        switch (type) {
            case 1:
                printf("%-15s %-10s %-15s %-15s\n", "Name", "Number", "Email", "Address");
                printf("%-15s %-10s %-15s %-15s\n", name, number, email, address);
                break;
            case 2:
                printf("%-15s %-10s\n", "Name", "Number");
                printf("%-15s %-10s\n", name, number);
                break;
            case 3:
                printf("%-15s %-15s\n", "Name", "Email");
                printf("%-15s %-15s\n", name, email);
                break;
            case 4:
                printf("%-15s %-15s\n", "Name", "Address");
                printf("%-15s %-15s\n", name, address);
                break;
            default:
                printf("%-15s %-10s %-15s %-15s\n", "Name", "Number", "Email", "Address");
                printf("%-15s %-10s %-15s %-15s\n", name, number, email, address);
        }

    } else {
        cout << "\"" + key + "\" not found.\n" << endl;
        wait();
    }

} else {        
    cout << "Contact list is empty.\n" << endl;
    wait();
}

第一个 printf 打印正常，但第二个会抛出异常，似乎与我如何传递字符串值无关。

Answer 1

printf 的“%s”需要一个 char* 作为参数，而不是 std::string。因此 printf 会将您的字符串对象解释为指针并尝试访问对象的第一个 sizeof(char*) 字节给出的内存位置，这会导致访问冲突，因为这些字节并不是真正的指针.

要么使用字符串的 c_str 方法获取 char*，要么不使用 printf。