Two-dimensional arrays

This program shows how to dynamically construct a two-dimensional array that can specify the number of rows and columns of an array:

1 int**make2darray (intRowsintcols) {2     int**x,i;3X=malloc (rows*sizeof(*x));4      for(i=0; i<rows;i++){5X[i]=malloc (cols*sizeof(**x));6     }7     returnx;8}

A two-dimensional array can be manipulated as a matrix with special matrices such as triangular matrices, sparse matrices, and unit matrices.

The program is used to determine whether a matrix is a unit matrix:

1#include <stdio.h>2 #defineN 43 intMainvoid)4 {5     intI,j,a[n][n];6     intCount=0;7      for(i=0; i<n;i++){8          for(j=0; j<n;j++){9scanf"%d",&A[i][j]); Ten         } One     }  A      for(i=0; i<n;i++){ -          for(j=0; j<n;j++){ -             if(i==j) { the                 if(a[i][j]==1){ -count++;  -                 }  -             } +             Else{ -                 if(a[i][j]==0){ +count++; A                 } at             } -              -         }  -     } -     if(count==n*N) { -printf"Yes");  in     } -     Else{  toprintf"No"); +     } -     return 0; the}

where n in the macro definition is the column of the matrix, you can set your own size according to your own needs.

2016-10-24 12:12:49

Two-dimensional arrays