[Error] missing template arguments before '(' token
时间: 2024-02-01 07:04:37 浏览: 45
这个错误通常是因为在使用一个模板时没有提供必要的模板参数。例如,如果你定义了一个函数模板:
```
template<typename T>
void foo(T arg) {
// ...
}
```
在调用该模板时,必须提供模板参数:
```
foo<int>(42);
```
如果你忘记了提供模板参数,就会出现上面的错误。请检查你的代码,看看是否有任何未提供模板参数的模板使用。
相关问题
[Error] missing template arguments before 'aSt'
This error message indicates that there are missing template arguments before the variable name "aSt".
In C++, templates are used to create generic functions or classes that can work with different data types. When declaring a template function or class, you need to specify the template parameters inside angle brackets "< >".
For example, if you want to create a template function that takes two arguments of type T and returns their sum, you would write:
```
template <typename T>
T sum(T a, T b) {
return a + b;
}
```
In this case, "typename T" is the template parameter.
If you forget to specify the template parameters when declaring a variable of a templated type, you will get the "missing template arguments" error.
For example, if you have a class template called "MyClass" that takes two template parameters, and you try to declare a variable of type "MyClass" without specifying the template arguments, you will get this error:
```
template <typename T1, typename T2>
class MyClass {
// class implementation
};
int main() {
MyClass aSt; // error: missing template arguments before 'aSt'
return 0;
}
```
To fix this error, you need to specify the template arguments when declaring the variable. For example:
```
int main() {
MyClass<int, double> aSt; // OK
return 0;
}
```
In this case, we are declaring a variable of type "MyClass" with the template arguments "int" and "double".
missing template arguments before 异常解决
这个错误通常出现在模板函数或类使用时没有提供足够的模板参数。你需要确保在使用模板函数或类时提供正确数量和类型的模板参数。
例如,如果你有一个模板类:
```
template <typename T>
class MyClass {
public:
// class definition
};
```
如果你在使用它时没有指定模板参数,就会出现 "missing template arguments before" 的错误:
```
MyClass obj; // error: missing template arguments before ‘obj’
```
要解决这个错误,你需要提供正确的模板参数,例如:
```
MyClass<int> obj;
```
如果你需要在多个地方使用相同的模板参数,可以将其提取为一个类型别名或模板别名:
```
using MyIntClass = MyClass<int>;
MyIntClass obj;
```
或者:
```
template <typename T>
using MyType = MyClass<T>;
MyType<int> obj;
```