C++ 错误：命名空间“std”中没有名为“vector”的类型
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error: no type named 'vector' in namespace 'std'
提问by Lidia Freitas
Why this is happening?
为什么会发生这种情况？
error: no type named 'vector' in namespace 'std'; did you mean 'hecto'? void askForVector(std::vector * vector);
错误：命名空间“std”中没有名为“vector”的类型；您指的是 'hecto' 吗？void askForVector(std::vector * vector);
#include <iostream>
#include <vector>
void askForVector(std::vector * vector);
int main()
{
std::vector<int> vector;
int size;
askForVector(&vector);
std::cout << "\nsize: " << vector.size() << std::endl;
std::cout << vector.at(0);
}
void askForVector(std::vector * vector)
{
int size;
std::cout << "please insert the size of vector to order: ";
std::cin >> size;
vector->resize(size);
for(int i = 0; i<size; i++){
std::cout << "please insert a value for the " << i+1 << " position: " ;
std::cin >> vector[i];
}
for(int j: *vector)
std::cout << ":"<<j;
std::cout << ":\n";
}
回答by Mike Seymour
vectoris a template, not a type. Either specify a particular specialisation:
vector是模板，而不是类型。要么指定一个特定的专业：
void askForVector(std::vector<int> * vector);
or make the function generic
或使函数通用
template <typename T>
void askForVector(std::vector<T> * vector);
You might be better off using a reference rather than a pointer:
使用引用而不是指针可能会更好：
void askForVector(std::vector<int> & vector);
or returning the vector by value:
或按值返回向量：
std::vector<int> askForVector() {
std::vector<int> vector;
// your code here
return vector;
}
to avoid errors like
避免错误，例如
std::cin >> vector[i]; // should be (*vector)[i]
回答by Marco A.
There are multiple issues:
有多个问题：
vector is a template, not a type, you need the template argument list e.g.
vector<int>in the function signatureSince you're passing a pointer to a vector you need to dereference it beforeusing the subscript operator
std::cin >> vector[i]; // wrong std::cin >> (*vector)[i]; // correct
vector 是模板，而不是类型，您需要模板参数列表，例如
vector<int>在函数签名中由于您将指针传递给向量，因此您需要在使用下标运算符之前取消引用它
std::cin >> vector[i]; // wrong std::cin >> (*vector)[i]; // correct
The following could work:
以下可能有效：
#include <iostream>
#include <vector>
void askForVector(std::vector<int> * vector);
int main()
{
std::vector<int> vector;
int size;
askForVector(&vector);
std::cout << "\nsize: " << vector.size() << std::endl;
std::cout << vector.at(0);
}
void askForVector(std::vector<int> * vector)
{
int size;
std::cout << "please insert the size of vector to order: ";
std::cin >> size;
vector->resize(size);
for (int i = 0; i<size; i++){
std::cout << "please insert a value for the " << i + 1 << " position: ";
std::cin >> (*vector)[i];
}
for (int j : *vector)
std::cout << ":" << j;
std::cout << ":\n";
}
