为此题提供两种做法:一是把此数列连续的奇数项和偶数项结合起来构成一个新数列,它就变成-1,-1,-1,...,-1共50项这样一个数列,C编程当然就很简单了。另一种是用一个for循环遍历1~100,计数变量为奇数时向和累加计数变量的值,而计数变量为偶数时从和减去计数变量的值。举例代码如下:
(1)
#include "stdio.h"
int main(int argc,char *argv[]){
printf("1-2+3-4+...+99-100 = %d\n",(1-2)*50);
return 0;
}
运行结果如下:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/7e3e6709c93d70cf6602c7a4f2dcd100bba12b9a?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
(2)
#include "stdio.h"
int main(int argc,char *argv[]){
int s,i;
for(s=0,i=1;i<101;i++)//遍历1~100
s += i&1 ? i : -i;//i为奇数时取正向s累加,i为偶数时取负向s累加
printf("1-2+3-4+...+99-100 = %d\n",s);
return 0;
}
运行结果如下:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/0823dd54564e9258eebbe8479682d158cdbf4e8f?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)