#include＜stdio.h＞ void main() { int i,j,s,a[][3]={{1,2,3},{4,5，6},{7，8，9}}; for(s=0,i=0;i＜3;i++) switch(i) { case 0: case 1: case 2:for(j=0;j＜3;j++)s+=a[i][j];break; } printf("s=%d\n",s); }
s=21