我error: ‘data_structure’ was not declared in this scope在編譯以下代碼時遇到錯誤：。
我假設錯誤發生在：
root = data_structure.insert(root, data[data_ind]);data_structure.insert(data[data_ind]);TreapNode<int> *res = data_structure.search(root, search_data[s_data_ind]);bool res = data_structure.search(search_data[s_data_ind]);
但我不知道我應該糾正什么。
完整代碼：https : //gist.github.com/theabc50111/05651b8c125feaaff5f80f15deb535f4
部分代碼：
void test(string file_name_it, string file_name_st, string type_record)
{
int var_range = 30; // the range of variable in skip list
int min_data_qty = 10; // set the min amount of imput data
int max_data_qty = 30; // set the max amount of imput data
clock_t i_begin_time, i_end_time, s_begin_time, s_end_time;
vector<double> i_time_records, s_time_records;
vector<int> search_data = gen_rand_array(100000, var_range); // generate search data
srand(time(NULL));
for (int data_qty=min_data_qty; data_qty<=max_data_qty; data_qty )
{
if (type_record.compare("hash table"))
{
Hash<int> data_structure(pow(2,data_qty));
cout << "start test hash table insert & search\n";
}
else if (type_record.compare("skip list"))
{
SkipList<int> data_structure;
cout << "start test Skip List insert with probability :" << data_structure.p << endl;
}
else if (type_record.compare("sorted array"))
{
cout << "start test sorted array insert & search\n";
SortedArray<int> data_structure;
}
else if (type_record.compare("treap"))
{
cout << "start test treap insert & search\n";
TreapNode<int> data_structure;
TreapNode<int> *root = nullptr;
}
vector<int> data = gen_rand_array(pow(2,data_qty),var_range);
i_begin_time = clock();
for (int data_ind=0; data_ind<data.size(); data_ind )
{
if (type_record.compare("treap"))
{
root = data_structure.insert(root, data[data_ind]);
}
else
{
data_structure.insert(data[data_ind]);
}
}
i_end_time = clock();
s_begin_time = clock();
for (int s_data_ind=0; s_data_ind<search_data.size(); s_data_ind )
{
if (type_record.compare("treap"))
{
TreapNode<int> *res = data_structure.search(root, search_data[s_data_ind]);
// (res == NULL)? cout << "Not found\n" : cout << "found\n";
}
else
{
bool res = data_structure.search(search_data[s_data_ind]);
(res == false)? cout << search_data[s_data_ind] <<" is not found\n" : cout << search_data[s_data_ind] << " found\n";
}
}
s_end_time = clock();
double i_spend_time = (double)(i_end_time-i_begin_time) / CLOCKS_PER_SEC;
double s_spend_time = (double)(s_end_time-s_begin_time) / CLOCKS_PER_SEC;
cout << "K=" << data_qty << ", insert time: " << i_spend_time << ". search time: " << s_spend_time << endl;
i_time_records.push_back(i_spend_time);
s_time_records.push_back(s_spend_time);
output_file(file_name_it, type_record, i_time_records);
output_file(file_name_st, type_record, s_time_records);
// data_structure.print();
}
}
int main(){
test("sa_i_time.csv", "sa_s_time.csv", "sorted array");
return 0;
}
錯誤：
/home/ywt01/Documents/codes/nccu_cs_hw/DataStructure_HW/HW3/hw3.cpp: In function ‘void test(std::string, std::string, std::string)’:
/home/ywt01/Documents/codes/nccu_cs_hw/DataStructure_HW/HW3/hw3.cpp:800:17: error: ‘root’ was not declared in this scope
800 | root = data_structure.insert(root, data[data_ind]);
| ^~~~
/home/ywt01/Documents/codes/nccu_cs_hw/DataStructure_HW/HW3/hw3.cpp:800:24: error: ‘data_structure’ was not declared in this scope
800 | root = data_structure.insert(root, data[data_ind]);
| ^~~~~~~~~~~~~~
/home/ywt01/Documents/codes/nccu_cs_hw/DataStructure_HW/HW3/hw3.cpp:804:17: error: ‘data_structure’ was not declared in this scope
804 | data_structure.insert(data[data_ind]);
| ^~~~~~~~~~~~~~
/home/ywt01/Documents/codes/nccu_cs_hw/DataStructure_HW/HW3/hw3.cpp:815:40: error: ‘data_structure’ was not declared in this scope
815 | TreapNode<int> *res = data_structure.search(root, search_data[s_data_ind]);
| ^~~~~~~~~~~~~~
/home/ywt01/Documents/codes/nccu_cs_hw/DataStructure_HW/HW3/hw3.cpp:815:62: error: ‘root’ was not declared in this scope
815 | TreapNode<int> *res = data_structure.search(root, search_data[s_data_ind]);
| ^~~~
/home/ywt01/Documents/codes/nccu_cs_hw/DataStructure_HW/HW3/hw3.cpp:820:28: error: ‘data_structure’ was not declared in this scope
820 | bool res = data_structure.search(search_data[s_data_ind]);
| ^~~~~~~~~~~~~~
Build finished with error(s).
uj5u.com熱心網友回復：
變數data_structure和root僅在塊作用域 pf if 陳述句中活著且可見，例如在此 if 陳述句中宣告它們
else if (type_record.compare("treap"))
{
cout << "start test treap insert & search\n";
TreapNode<int> data_structure;
TreapNode<int> *root = nullptr;
}
如果你甚至會寫
else if (type_record.compare("treap"))
TreapNode<int> data_structure, *root = nullptr;
盡管如此，if 陳述句的子陳述句形成了它自己的塊作用域。那就是上面的陳述句等價于
else if (type_record.compare("treap"))
{
TreapNode<int> data_structure, *root = nullptr;
}
如果函式的其他部分需要變數，則需要在 if 陳述句之外宣告變數。
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