C ++ 17では、Fortran 90以降、Fortranにあった通常の多次元配列はまだありません。

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double a[n][n]



std::array<std::array<double, n>, n>



, . . (n) runtime. new double[n][n]



( , new, runtime-). :

double **a = new double *[n]; //   n   double
for (int i = 0; i != n; ++i)
  {
    a[i] = new double[n];
  }

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. i- j- a[i][j]. . a — . , . , i- j- , , . ( . .) . std::vector<std::vector<



double>>



.



UPD 2016-12-11 0:00. . , .



:

double *a = new double[n * n];

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, i- j- : a[i * n + j]. .



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Fortran . i- j- .



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Fortran 90 . 26 . 26 Fortran'. C++ .



:

REAL, ALLOCATABLE :: A (:,:)
...
ALLOCATE (A (N,N))

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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, C . , , , , . :

void f (int a[2])
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

:

void f (int a[])
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

:

void f (int *a)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. , «» a «» b, . , , , , / , , ( C89, ). , , a[2] — b[3]. , a[2], b[3], commit . , Fortran'.



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UPD 2016-12-10 14:03. selgjos, , C99 VLA - . , : double a[n][n]



, . . . :

double (*a)[n] = malloc (n * n * sizeof (double));
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

a — , . n n, . i- j- a[i][j]. - , :

void f (int n, double a[n][n])
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , C . Fortran. C++ - .



UPD 2016-12-12 19:12. :

, . . , , , , . , , , . .

UPD 2016-12-12 22:49. :

C++ Fortran C. , , , . Fortran «» , C++ — . .