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How to print dimensions of multidimensional array in C++

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  • Difficulty Level : Hard
  • Last Updated : 24 Jan, 2022

Create a function that prints multidimensional array size by dimensions i.e.:
Examples: 
 

Input : 
int a[2][3][4];
printDimensions(a);
Output :
2x3x4

Input :
int b[5][6];
printDimensions(a);
Output :
5x6

 

To solve this problem we should use template function to figure out the size of current array. Then we call this function recursively till the last dimension. For last dimension the boundary overridden template function should be used. The implementation of the idea:
 

CPP




// C++ program to print dimensions of a
// multidimensional array
#include <iostream>
 
template <typename T, size_t N>
void printDimensions(const T (&a)[N])
{
    std::cout << N;
}
 
template <typename T, size_t N, size_t M>
void printDimensions(const T (&a)[N][M])
{
    std::cout << N << "x";
    printDimensions(a[0]);
}
 
int main()
{
    int a[2][3][4];
    printDimensions(a);
    return 0;
}


Output: 

2x3x4

 

Pay attention the order of two template functions. It won’t compile if you switch them.
There is one more way to get the same results by using language template features:
 

CPP




// C++ 14 program to print dimensions of a
// multidimensional array
#include <iostream>
#include <type_traits>
 
template <typename T>
std::enable_if_t<std::rank<T>::value == 1>
printDimensions(const T& a)
{
    std::cout << std::extent<T>::value;
}
 
template <typename T>
std::enable_if_t<std::rank<T>::value != 1>
printDimensions(const T& a)
{
    std::cout << std::extent<T>::value << "x";
    printDimensions(a[0]);
}
 
int main()
{
    int a[2][3][4];
    printDimensions(a);
    return 0;
}


Output: 

2x3x4

 

If you think that template names are too long to print you are not alone. There are short aliases in C++17: 
std::extent_v for std::extent::value and std::rank_v for std::rank::value
 


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