用malloc为二维数组分配空间并初始化为1

 int main(){
  5         //int arr[5][5];
  6         int **arr;
  7         arr = (int**)malloc(sizeof(int*) * 5);
  8         int i = 0;
  9         int j = 0;
 10         for(i = 0;i<5;i++){
 11                 arr[i] = (int *)malloc(sizeof(int) * 5);
 12         //      memset(arr[i],1,(sizeof(int)*5));
 13         }
 14         for(i = 0;i<5;i++){
 15                 for(j = 0;j<5;j++){
 16                         arr[i][j] = 1;
 17                         printf("arr[%d][[%d]=%d\n",i,j,arr[i][j]);
 18                 }
 19         }
 20         //printf("\n");
 21         for(i = 0;i<5;i++){
 22                 free(arr[i]);
 23         }
 24         free(arr);
 25         return 0;
 26 }