#include "stdio.h"
int main(int argc,char *argv[]){
double a1,an,d,t;
int n;
printf("Please enter a1, an & d(R:)...\n");
scanf("%lf%lf%lf",&a1,&an,&d);
for(n=1,t=a1;t<an;t+=d,n++);
if(t-an){
printf("Input error, exit...\n");
return 0;
}
printf("The SUM are %g\n",(a1+an)/2*n);
return 0;
}
运行样例:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/77094b36acaf2edd786df280831001e93901933f?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)