c++編程：從鍵盤給壹個4行4列的int型數組輸入數據，求出該數組的主對角線之和並寫入文件c：\data.txt

#define?N?4

int?main()?{

int?a[N][N],i,j,sum?=?0;

FILE?*fw?=?fopen("C:\\data.txt","wt");

if(fw?==?NULL)?{

printf("打開文件失敗。\n");

return?1;

}

printf("輸入%d個整數(空格隔開):\n",N?*?N);

for(i?=?0;?i?<?N;?++i)?{

for(j?=?0;?j?<?N;?++j)?{

scanf("%d",&a[i][j]);

if(i?==?j)?sum?+=?a[i][j];

}

}

printf("%d",sum);

fprintf(fw,"%d",sum);

fclose(fw);

return?0;

}