错误:将'long int(*)[4]'分配给'long int [4] [4]'时类型不兼容

本文介绍了错误:将'long int(*)[4]'分配给'long int [4] [4]'时类型不兼容的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试构建自己的Matrix类型，该类型作用于具有多维数组的标准C矩阵行.到目前为止，这是我的实现:

I am trying to build my own Matrix type which acts line an standard C matrix with multidimensional arrays. So far, this is my implementation:

#include <iostream> /** * To build it use: * g++ -std=c++11 test_template_initicialization.cpp -o main */ template <int width, int height> struct Matrix { long int _data[height][width]; Matrix() { } Matrix(long int matrix[height][width]) : _data(matrix) { } /** * Overloads the `[]` array access operator, allowing you to access this class objects as the * where usual `C` arrays. * * @param line the current line you want to access * @return a pointer to the current line */ long int* operator[](int line) { return this->_data[line]; } /** * Prints a more beauty version of the matrix when called on `std::cout<< matrix << std::end;` */ friend std::ostream &operator<<( std::ostream &output, const Matrix &matrix ) { int i, j; for( i=0; i < height; i++ ) { for( j=0; j < width; j++ ) { output << matrix._data[i][j] << ", "; } output << matrix._data[i][j] << "\n"; } return output; } }; /** * C++ Matrix Class * stackoverflow/questions/2076624/c-matrix-class */ int main (int argc, char *argv[]) { Matrix<3, 3> matrix; std::cout << matrix << std::endl; matrix[0][0] = 911; std::cout << matrix << std::endl; std::cout << matrix[0] << std::endl; std::cout << matrix[0][0] << std::endl; Matrix<4,4> matrix2 = { 0 }; }

构建最后一个示例Matrix<4,4> matrix2 = { 0 };时，出现类型不兼容错误:

When build the last example Matrix<4,4> matrix2 = { 0 }; I am getting incompatible types error:

D:\test_template_initicialization.cpp: In instantiation of 'Matrix<width, height>::Matrix(long int (*)[width]) [with int width = 4; int height = 4]': D:\test_template_initicialization.cpp:67:29: required from here D:\test_template_initicialization.cpp:16:56: error: incompatible types in assignment of 'long int (*)[4]' to 'long int [4][4]' Matrix(long int matrix[height][width]) : _data(matrix)

错误的主要部分是'long int (*)[4]' to 'long int [4][4]'. long int (*)[4]来自matrix2 = { 0 };，而long int [4][4]是我的标准类模板声明long int _data[height][width];.

The main part of the error is 'long int (*)[4]' to 'long int [4][4]'. The long int (*)[4] is coming from the matrix2 = { 0 }; and the long int [4][4] is my standard class template declaration long int _data[height][width];.

我可以修复我的Matrix构造函数，以便它可以接受来自matrix2 = { 0 };初始化调用的long int (*)[4]吗?

Can I fix my Matrix constructor, so it can accept this long int (*)[4] coming from matrix2 = { 0 }; initialization call?

推荐答案

在以下链接的帮助下，我设法对其进行了修复:

I managed to fix it, with the help of the following links:

en.cppreference/w/cpp/utility/initializer_list

从'int'到'int(*)的无效转换[3] 'c ++

使用多维std :: initializer_list

用括号括起来的初始化程序列表构造器

C ++矩阵类

java是否等效于python __call__?

C ++函子-及其用途

返回函数中的数组

在C ++中使用C标头时，我们应该使用std ::或全局名称空间中的函数吗?

std :: assert发生了什么

没有依赖模板的参数参数

可选模板参数

en.cppreference/w/cpp/utility/initializer_list

Invalid Conversion from 'int' to 'int(*)[3]' c++

Using multidimensional std::initializer_list

Brace-enclosed initializer list constructor

C++ Matrix Class

Does java have an equivalent to python __call__?

C++ Functors - and their uses

Return array in a function

When using C headers in C++, should we use functions from std:: or the global namespace?

What happened to std::assert

There are no arguments that depend on a template parameter

Optional Template parameter

固定代码:

#include <cassert> #include <iostream> template <unsigned int array_width, typename array_datatype=long int> struct Array { array_datatype _data[array_width]; Array() { } Array(std::initializer_list< array_datatype > raw_data) { unsigned int data_size = raw_data.size(); unsigned int column_index = 0; // std::cout << data_size << std::endl; if( data_size == 1 ) { array_datatype initial = *(raw_data.begin()); for( ; column_index < array_width; column_index++ ) { this->_data[column_index] = initial; } } else { assert(data_size == array_width); for( auto column : raw_data ) { this->_data[column_index] = column; column_index++; } } } /** * Overloads the `[]` array access operator, allowing you to access this class objects as the * where usual `C` arrays. * * @param line the current line you want to access * @return a pointer to the current line */ array_datatype* operator[](int line) { return this->_data; } /** * Prints a more beauty version of the matrix when called on `std::cout<< matrix << std::end;` */ friend std::ostream &operator<<( std::ostream &output, const Array &matrix ) { unsigned int column; output << "{"; for( column=0; column < array_width; column++ ) { output << matrix._data[column]; if( column != array_width-1 ) { output << ", "; } } output << "}"; return output; } }; template <unsigned int matrix_width, unsigned int matrix_height, typename matrix_datatype=long int> struct Matrix { matrix_datatype _data[matrix_height][matrix_width]; Matrix() { } Matrix(matrix_datatype initial) { unsigned int line; unsigned int column; for( line=0; line < matrix_height; line++ ) { for( column=0; column < matrix_width; column++ ) { this->_data[line][column] = initial; } } } Matrix(std::initializer_list< std::initializer_list< matrix_datatype > > raw_data) { // std::cout << raw_data.size() << std::endl; assert(raw_data.size() == matrix_height); // std::cout << raw_data.begin()->size() << std::endl; assert(raw_data.begin()->size() == matrix_width); unsigned int line_index = 0; unsigned int column_index; for( auto line : raw_data ) { column_index = 0; for( auto column : line ) { this->_data[line_index][column_index] = column; column_index++; } line_index++; } } /** * Overloads the `[]` array access operator, allowing you to access this class objects as the * where usual `C` arrays. * * @param line the current line you want to access * @return a pointer to the current line */ matrix_datatype* operator[](int line) { return this->_data[line]; } /** * Prints a more beauty version of the matrix when called on `std::cout<< matrix << std::end;` */ friend std::ostream &operator<<( std::ostream &output, const Matrix &matrix ) { unsigned int line; unsigned int column; output << "{"; for( line=0; line < matrix_height; line++ ) { output << "{"; for( column=0; column < matrix_width; column++ ) { output << matrix._data[line][column]; if( column != matrix_width-1 ) { output << ", "; } } if( line != matrix_height-1 ) { output << "}, "; } else { output << "}"; } } output << "}"; return output; } }; void array_tests() { std::cout << "Array tests" << std::endl; Array<3, long int> array; std::cout << array << std::endl; std::cout << array[0] << std::endl; Array<3> array2 = {0,0,0}; std::cout << "array2: " << array2 << std::endl; Array<3> array3 = {3}; std::cout << "array3: " << array3 << std::endl; } void matrix_tests() { std::cout << "Matrix tests" << std::endl; Matrix<3, 3, long int> matrix; std::cout << matrix << std::endl; matrix[0][0] = 911; std::cout << matrix << std::endl; std::cout << matrix[0] << std::endl; std::cout << matrix[0][0] << std::endl; Matrix<3, 3> matrix2{ {0,0,0}, {0,0,0}, {0,0,0} }; std::cout << matrix2 << std::endl; Matrix<3, 3> matrix3 = { 3 }; std::cout << matrix3 << std::endl; Matrix<3, 1, long int> matrix4 = { 4 }; std::cout << matrix4 << std::endl; } /** * To build it use: * g++ -std=c++11 main.cpp -o main */ int main (int argc, char *argv[]) { matrix_tests(); std::cout << std::endl; array_tests(); }

运行此命令，您将得到:

Running this, you get:

Matrix tests {{4200800, 0, -928274330}, {32765, 14354248, 0}, {-1499063668, 0, 24}} {{911, 0, -928274330}, {32765, 14354248, 0}, {-1499063668, 0, 24}} 0x65fde0 911 {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}} {{3, 3, 3}, {3, 3, 3}, {3, 3, 3}} {{4, 4, 4}} Array tests {0, 1875566066, 0} 0x65fdf4 array2: {0, 0, 0} array3: {3, 3, 3}