要求实现一个计算m~n（m<n）之间所有整数的和的简单函数
int sum(int m, int n);
int main()
{
int m, n;
scanf("%d %d", &m, &n);
printf("sum = %d\n", sum(m, n));
return 0;
}
int sum(int ma, int na)
{int suml;
suml=ma;
while(ma<na)
{
++ma;
suml=suml+ma;
}
return suml;
}