C & C ++ dynamic two-dimensional array

1. Dynamic two-dimensional array

　　Objective: to facilitate a configuration matrix of m rows and n columns

 

2. A simple realization

　　Here to write a function template

　　C ++ compiler separation function template is not supported, it is necessary to implement declarations are written in a file

　　myarray.h：

. 1  #ifndef TESTCPLUS_MYARRAY_H
 2  #define TESTCPLUS_MYARRAY_H
 . 3  
. 4 #include <the iostream>
 . 5  the using  namespace STD;
 . 6 Template <typename T>
 . 7  / * 
. 8  functions: malloc space applications partial success, partial failure, the successful recovery portion
 9  * / 
10  static  void freePartMatrix (T ** Pary, int I)
 . 11  {
 12 is      for ( int J = I- . 1 ; J> = 0 ; J, ) {
 13 is          IF (! Pary [J] = nullptr a) {
 14              Free(Pary [J]);
 15              Pary [J] = nullptr a;
 16          }
 . 17      }
 18 is      Free (Pary);
 . 19  }
 20 is  / * 
21 is  the function: obtaining a two-dimensional array of m rows and n columns, or a m rows and n columns of the matrix
 22  function template
 23 is  * / 
24 template <typename T>
 25 T ** getMNMatrix ( int m, int n-)
 26 is  {
 27      IF (m < . 1 || n-< . 1 ) {
 28          return nullptr a;
 29      }
 30      T ** pary = nullptr;
31     pary = (T**)malloc(m*sizeof(T*));
32     if(pary == nullptr) {
33         return nullptr;
34     }
35     for(int i=0;i<m;++i) {
36         pary[i] = (T*)malloc(n*sizeof(T));
37         if(pary[i] == nullptr) {
38             freePartMatrix(pary,i);
39             pary = nullptr;
40             return nullptr;
41         }
42         memset(pary[i],0,n*sizeof(T));
43     }
44     return pary;
45 }
46 
47 template <typename T>
48 void print_matrix(T** ary,int m,int n)
49 {
50     if(ary == nullptr) {
51         cout<<"Empty Matrix"<<endl;
52     }
53     for(int i=0;i<m;++i){
54         for(int j=0;j<n;++j) {
55             cout<<ary[i][j]<<"  ";
56         }
57         cout<<"\n";
58     }
59 }
60 #endif //TESTCPLUS_MYARRAY_H

　　myarray.cpp

1 #include "myarray.h"

 

　　main.cpp

1 int m,n;
2 cin>>m>>n;
3 int** array = getMNMatrix<int>(m,n);
4 print_matrix<int>(array,m,n);