矢量：内存范围错误

Question

之前，我一直在 CodeBloks 中使用 C++ 进行一些编程，从一段时间以来，我开始在 MS Studio 中进行编程。目前我正在编写书中的一个小游戏：编程：使用 C++ 的原则和实践。第 5 章的练习 12。 我一直在互联网上四处寻找，以修复无论我尝试什么都会不断发生的范围内存错误（请参阅打印屏幕链接）。 关于程序的描述在代码本身中。 我还确实将向量设置为硬编码（如果我说得对的话）大小，以使程序不再抱怨它们的内存范围错误。

注意：是的，这也是一个学校练习/练习。但是我宁愿问我做错了什么，然后从互联网上复制粘贴代码..

请查看我的代码并查看，否则我在向量方面犯了一些错误，因为这可能是我的错误的来源。

更新：作为本主题的答案。 Link to update

错误：

Unhandled exception at 0x7529CBC2 in Tweede project.exe: Microsoft C++ exception: Range_error at memory location 0x006FF510.

程序：

#include "std_lib_facilities.h"

int main(){
    bool while_bit = false;
    vector<int>bulls_cows(4);
    vector<int>inputs_arr(4);

    //Generate 4 random numbers.
    for (int a = 0; a < 4; ++a){
        bulls_cows[a] = a + 1;//randint(a) % 9 + 0; //random number between 0 and 9.
    }
    //bulls_cows[1] = randint(10);
    cout << "For this game, called Bulls and Cows, you have to guess the four right numbers between 0 and 9.\n";
    cout << "When one or more digets are right and in the right position the program will say the number of Bulls.\n";
    cout << "When one or more digets are right but not in the right position the program will say the number of Cows.\n";
    cout << "Please enter 4 number by filling in ONE positive diget and press enter. Do this four times and wait for the result.\n";

    for (int z = 0; z < 4; ++z) {
        cout << bulls_cows[z] << "\n";
    }

    while (while_bit == false) {
        int input = 0; //Reset of input, cows and bulls every round.
        int cows = 0;
        int bulls = 0;

        cin >> input;

        //Test for legit input. If legit then it writes it to the array called "input_arr"
        if (input < 0 || input > 9) {
            cout << "Number must be between 0 and 9.\n";
        }
        else {
            inputs_arr.push_back(input);
        }
        //Check or 4 numbers have been given.
        if (sizeof(inputs_arr) < 4) {
            //Check for equal numbers on same spot.
            for (int b = 0; b < 4; ++b) {
                if (inputs_arr[b] == bulls_cows[b]) {
                    bulls + 1;
                }
            }
            //Check for a number in all spots.
            for (int c = 0; c < 4; ++c) {
                if (inputs_arr[c] == bulls_cows[0] || bulls_cows[1] || bulls_cows[2] || bulls_cows[3]) {
                    cows +1;
                }
            }
        }

        if (bulls < 4) {
            cout << "You did not guess the right combination.\n";
            cout << "Number of bulls: " << bulls << "\n";
            cout << "Number of cows: " << cows << "\n";
            inputs_arr[0, 0, 0, 0]; //Empty array.
        }

        if (bulls == 4) {
            cout << "You guessed the right combination!\n";
            while_bit = true;
    }

    }

    keep_window_open(); //To keep terminal open since MS Studio doesn't itself.

    return 0;
}

Answer 1

将sizeof 运算符与inputs_array 向量一起使用将为您提供该对象在内存中的大小（以字节为单位）。也许你以前用过这个数组。

相反，我认为您想要推入向量中的项目数。 std::vector 有一个名为 size 的函数，它给出推送给它的项目数。

Answer 2

在 Visual Studio 中，你真的应该，真的将警告级别设置为 4 级。然后编译器会告诉你一些你尝试做的奇怪的事情。

例如：

 warning C4552: '+': operator has no effect; expected operator with side-effect 1>
                bulls + 1;

您计算结果，但从不将其存储在任何地方。奶牛也一样。

error C4548: expression before comma has no effect; expected expression with side-effect
            inputs_arr[0, 0, 0, 0]; //Empty array.

这不是清空数组的方法。要删除所有元素，请执行inputs_arr.clear();。

warning C4127: conditional expression is constant
        if (sizeof(inputs_arr) < 4) {

正如我们已经看到的，sizeof 是矢量对象的大小（始终相同），而不是它所包含的元素数量。

---

然后有一些逻辑错误。

vector<int>inputs_arr(4);

这将创建一个最初包含 4 个整数的向量。

但稍后当你这样做时

inputs_arr.push_back(input);

它将 更多 个元素添加到向量中，因此现在它最多可以容纳 8 个整数。您必须决定是要先创建完整尺寸的，还是要在进行时添加元素。但不是两者兼而有之。

另一个问题是条件

if (inputs_arr[c] == bulls_cows[0] || bulls_cows[1] || bulls_cows[2] || bulls_cows[3]) {

即使有 种语言可以在其中编写与此类似的条件，但在 C++ 中却不能。要将变量x 与其他几个值进行比较，您必须将其拼写出来：

if (x == y || x == z || x == w)

Answer 3

更新：（不确定或者我不得不将其添加到问题中或作为答案。如果有错误，请告诉我。我是堆栈溢出的新手；））

似乎有些语句/循环括号没有正确放置。我编辑了一下： 可悲的是，我的 intergers cows 和 bulls 似乎没有在第 61 行和第 62 行重置。任何人都知道我在那里可能做错了什么。

日志：

cin 没有循环。还编辑了 else-statement 'inputs_arr.pushback(input)' 并在其下方添加了所有 for 循环和语句。修复了部分cin问题。

将公牛、奶牛和输入整数替换到程序顶部，并在 false/if 语句的末尾重置。

将所有循环和语句放在 if-statement '(int b = 0; b

将 for 循环编辑为 >4，其中 couts “数组大小”以查看它具有哪些值。稍后会被删除，因为它仅用于测试。

#include "std_lib_facilities.h"

int main()
{
bool while_bit = false;
int input = 0;
int cows = 0;
int bulls = 0;
vector<int> bulls_cows(4); //size needed to prevent memory size error at line 11.
vector<int> inputs_arr;

//Generate 4 random numbers. Need to add seed later.
for (int a = 0; a < 4; ++a){
    bulls_cows[a] = randint(a) % 9 + 0; //random number between 0 and 9.
}

cout << "For this game, called Bulls and Cows, you have to guess the four right numbers between 0 and 9.\n";
cout << "When one or more digets are right and in the right position the program will say the number of Bulls.\n";
cout << "When one or more digets are right but not in the right position the program will say the number of Cows.\n";
cout << "Please enter 4 numbers by filling in ONE positive diget and press enter. Do this four times and wait for the result.\n";

for (int z = 0; z < 4; ++z) { //Gives the generated numbers for testing.
    cout << bulls_cows[z] << "\n";
}

while (while_bit == false) {

    cin >> input;

    //Test for legit input. If legit then it writes it to the array called "input_arr"
    if (input < 0 || input > 9) {
        cout << "Number must be between 0 and 9.\n";
    }
    else {
        inputs_arr.push_back(input);

        //Check or 4 numbers have been given.
        if (inputs_arr.size() > 3) {
            //Check for equal numbers on same spot.
            for (int b = 0; b < 4; ++b) {
                if (inputs_arr[b] == bulls_cows[b]) {
                    ++bulls;
                }
            }

            //Check for a number in all spots.
            for (int c = 0; c < 4; ++c) {
                if (inputs_arr[c] == bulls_cows[0] || inputs_arr[c] == bulls_cows[1] || inputs_arr[c] == bulls_cows[2] || inputs_arr[c] == bulls_cows[3]) {
                    ++cows;
                }
            }

            /*for (int x = 0; x < 4; ++x) { //Couts again the fresh entered numbers for a better overview.
                cout << "Size of array: " << inputs_arr[x] << "\n";
            }*/

            if (bulls < 4) {
                cout << "You did not guess the right combination.\n";
                cout << "Number of bulls: " << bulls << "\n";
                cout << "Number of cows: " << cows << "\n";
                int cows = 0; //Reset of cows and bulls each round.
                int bulls = 0;
                inputs_arr.clear(); //Empty the array.
                cout << "Please enter 4 numbers:\n";
            }

            if (bulls == 4) {
                cout << "You guessed the right combination!\n";
                while_bit = true;
            }
        }
    }
}

keep_window_open(); //To keep terminal open since MS Studio doesn't itself.

return 0;
}