编写函数求 a 到 b 之间所有偶数之和,用主函数调用,求1-100之间所有偶数之和,哪里错了？

Question

#include <stdio.h>
int desum(int a,int b)
{
int i,sum=0;
if(a%2==0)
i=a;
else i=a+1;
for(a%2==0?i=a:i=a+1;sum+=i;i+=2)
{
if(i==b)
break;
}
return(sum);
}
int main()
{
int a=1,b=100;
desum(a,b);
printf("1~100之间所有偶数的和=%d\n",desum);
return 0;
}

Answer 1

#include <stdio.h>

int desum(int a, int b)
{
int i, j, sum = 0;
if(a % 2 == 0) i = a; else i = a + 1;
if(b % 2 == 0) j = b; else j = b - 1;

for(; i <= j; i += 2)
sum += i;
return(sum);
}

int main()
{
int a = 1, b = 100, c;
c = desum(a, b);
printf("1~100之间所有偶数的和 = %d\n", c);
return 0;
}