尝试返回类的类型，但错误的模板参数

Question

我总共有5个函数重载&，+， - ，*和/只有一个类，只有一个动态创建的数组与arrSize作为私人成员。我也使用模板来普及类和它的重载函数。在我遇到的5个函数的每一个函数中，我都得到错误无效使用模板名称'SmartArray'而没有参数列表。这里是我的功能：

/* function description: overrides the & operator. Lets us concatenate two arrays together. 
    parameters:   const SmartArray& numArray is the right-hand array being concatenated to the left-hand array. 
    return value:   void 
*/ 
template <class ArrType> 
SmartArray<ArrType>& SmartArray::operator&(const SmartArray& numArray) const{ 
    SmartArray concatenate(arrSize+numArray.length()); // creating object with array large enough to hold both arrays. 
    for(int i=0; i<arrSize; i++)  // putting left-hand array into concatenated array 
     concatenate.elements[i] = elements[i]; 
    for(int i=arrSize; i<arrSize+numArray.length(); i++) // puts in right-hand array elements second 
     concatenate.elements[i] = numArray.elements[i-arrSize]; 

    return concatenate; 
} 

/* function description: overrides + operator. Lets us add the contents of two arrays together. 
    parameters:   const SmartArray& numArray is the right-hand array being added to the left-hand array. 
    return value:   SmartArray 
*/ 
template <class ArrType> 
SmartArray SmartArray::operator+(const SmartArray& numArray) const{ 
    SmartArray added; // initializes array to hold added arrays 
    if(arrSize > numArray.length()){ // checks which array is larger, then creates new array with the larger size 
     SmartArray added(arrSize); 
     for(int i=0; i<numArray.length(); i++) 
      added.elements[i] += numArray.elements[i]; 
     for(int i=numArray.length(); i<arrSize; i++) 
      added.elements[i] = numArray.elements[i]; 
    }else if(arrSize <= numArray.length()){ 
     SmartArray added(numArray.length()); 
     for(int i=0; i<arrSize; i++) 
      added.elements[i] += numArray.elements[i]; 
     for(int i=arrSize; i<numArray.length(); i++) 
      added.elements[i] = numArray.elements[i]; 
    } 
    return added; 
} 

/* function description: overrides + operator. Lets us subtract the contents of two arrays together. 
    parameters:   const SmartArray& numArray is the right-hand array being subtracted to the left-hand array. 
    return value:   SmartArray 
*/ 
template <class ArrType> 
SmartArray SmartArray::operator-(const SmartArray& numArray) const{ 
    SmartArray subtracted; // initializes array to hold subtracted arrays 
    if(arrSize > numArray.length()){ // checks which array is larger, then creates new array with the larger size 
     SmartArray subtracted(arrSize); 
     for(int i=0; i<numArray.length(); i++) 
      subtracted.elements[i] -= numArray.elements[i]; 
     for(int i=numArray.length(); i<arrSize; i++) 
      subtracted.elements[i] = numArray.elements[i]; 
    }else if(arrSize <= numArray.length()){ 
     SmartArray subtracted(numArray.length()); 
     for(int i=0; i<arrSize; i++) 
      subtracted.elements[i] -= numArray.elements[i]; 
     for(int i=arrSize; i<numArray.length(); i++) 
      subtracted.elements[i] = numArray.elements[i]; 
    } 
    return subtracted; 
} 

/* function description: overrides + operator. Lets us multiply the contents of two arrays together. 
    parameters:   const SmartArray& numArray is the right-hand array being multiplied to the left-hand array. 
    return value:   SmartArray 
*/ 
template <class ArrType> 
SmartArray SmartArray::operator*(const SmartArray& numArray) const{ 
    SmartArray multiplied; // initializes array to hold multiplied arrays 
    if(arrSize > numArray.length()){ // checks which array is larger, then creates new array with the larger size 
     SmartArray multiplied(arrSize); 
     for(int i=0; i<numArray.length(); i++) 
      multiplied.elements[i] *= numArray.elements[i]; 
     for(int i=numArray.length(); i<arrSize; i++) 
      multiplied.elements[i] = numArray.elements[i]; 
    }else if(arrSize <= numArray.length()){ 
     SmartArray multiplied(numArray.length()); 
     for(int i=0; i<arrSize; i++) 
      multiplied.elements[i] *= numArray.elements[i]; 
     for(int i=arrSize; i<numArray.length(); i++) 
      multiplied.elements[i] = numArray.elements[i]; 
    } 
    return multiplied; 
} 

/* function description: overrides + operator. Lets us divide the contents of two arrays together. 
    parameters:   const SmartArray& numArray is the right-hand array being divided to the left-hand array. 
    return value:   SmartArray 
*/ 
template <class ArrType> 
SmartArray SmartArray::operator/(const SmartArray& numArray) const{ 
    SmartArray divided; // initializes array to hold divided arrays 
    if(arrSize > numArray.length()){ // checks which array is larger, then creates new array with the larger size 
     SmartArray divided(arrSize); 
     for(int i=0; i<numArray.length(); i++) 
      divided.elements[i] /= numArray.elements[i]; 
     for(int i=numArray.length(); i<arrSize; i++) 
      divided.elements[i] = numArray.elements[i]; 
    }else if(arrSize <= numArray.length()){ 
     SmartArray divided(numArray.length()); 
     for(int i=0; i<arrSize; i++) 
      divided.elements[i] /= numArray.elements[i]; 
     for(int i=arrSize; i<numArray.length(); i++) 
      divided.elements[i] = numArray.elements[i]; 
    } 
    return divided; 
} 

随着第一个功能，我尝试使用

SmartArray<ArrType>& SmartArray::..... 

，但我得到了错误“‘模板类的SmartArray’不使用模板参数。”

Answer 1

无处不在您使用SmartArray类型，您需要包含要使用的模板类型。例如，

template <class ArrType> 
SmartArray<ArrType> SmartArray<ArrType>::operator&(const SmartArray<ArrType>& numArray) const{ 
    SmartArray<ArrType> concatenate(arrSize+numArray.length()); 

注意添加<ArrType>到numArray在参数列表中的声明和concatenate局部变量。我也从函数返回类型中删除了&，因为你不想返回一个对局部变量的引用。

您必须对其他功能进行类似的更改。