C语言:求数列2,-4,6,-8,10,-12,...,前100项之和及第100项的值,咋编程...答:代码文本:include "stdio.h"int main(int argc,char *argv[]){ int n,i,s;for(s=i=0,n=2;i<100;i++,n+=2)s += i&1 ? -n : n;printf("The sum are the %d\nThe last item is %d\n",s,(i&1 ? n-2 : 2-n));return 0;} ...