个回答

• 慕后端3326841

  2016-11-26 00:59:20

  #include <stdio.h>
  int main()
  {
      int i;
      int j=1;
      int count=0;
      int sum=0;
      for(i=1;i<100;i+=2)
      {
          sum+=i*j;
          j*=-1;
          count++;
          if(count==20)
          break;
      }
      printf("1-3+5-7……前20项的和为:%d\n",sum);
      return 0;
  }

  
  

  0

• 越飞越高

  2016-11-07 15:30:17

  #include<stdio.h>
   int main()
   {
     int i,j,sum1,sum2,sum;
     for(i=1,sum1=0;i<20;i=i+2)
         sum1+=i;
      for(j=-2,sum2=0;j>-21;j=j-2)
         sum2+=j;
       sum=sum1+sum2;
       printf("1-2+3-…-20=%d\n",sum);
       return 0;
   }

  0

• 他眼角的痣0

  2016-11-07 14:58:25

  类似的改成+4和-4

  0

• 他眼角的痣0

  2016-11-07 14:56:04

  #include<stdio.h>
  int main()
  {
    int i,j,sum1,sum2,sum;
    for(i=1,sum1=0;i<100;i=i+2)
        sum1=sum1+i;
     for(j=-2,sum2=0;j>-101;j=j-2)
        sum2=sum2+j;
      sum=sum1+sum2;
      printf("1-2+3-…-100=%d",sum);
      return 0;
  }

  0