#include "stdio.h"
int main(int argc,char *argv[]){
int a[3][3],s,i,j;
printf("Please enter data...\n");
for(i=0;i<3;i++)//输入3x3数组
for(j=0;j<3;scanf("%d",a[i]+j++));
printf("\n");
for(s=i=0;i<3;i++){//按3行3列输出并求对角线之和
for(j=0;j<3;printf("%10d",a[i][j++])){
if(i==j)//这两个if若写成if(i==j || i==2-j) s+=a[i][j];中间元素就只算一次
s+=a[i][j];
if(i==2-j)
s+=a[i][j];
}
printf("\n");
}
printf("The sum of the diagonal is %d\n",s);//对角线之和
printf("The second row sum total is %d\n",a[1][0]+a[1][1]+a[1][2]);//第二行总和
printf("The third line average is %g\n",(a[2][0]+a[2][1]+a[2][2])/3.0);//第三行平均值
return 0;
}
运行样例: