Question

c语言中1-3+5-7+9-11+13-15+17-19怎么做

Answer 1

int i=1;
int j=1;
int sum=0;
while(i<=19)
{
sum+=i*j;
i=i+2;
j=j*(-1);
}
printf("%d\n",sum);

Answer 2

#include <stdio.h>
main()
{
int i,s=1,d=0,t=0;
for (i=1;i<=19;i+=2)
{ t=i*s;
s=-s;
d=d+t;
}
printf("d=%d",d);
}

Answer 3

int getVal()
{
int result = 0;
int i, flag = 0;
for(i=1;i<20;i+=2)
{
if(!flag)
result += i;
else
result -= i;

flag = ~flag;
}

return result;
}

Answer 4

#include <stdio.h>
void main()
{
int s=0;
int i,j;
int l=1;
for (i=1;i<20;i=i+2)
{
j=i*l;
s=s+j;
l=-l;
}
printf ("%d",s);
}