小菜鸟提问~~~C语言的~~~~

#include<stdio.h>
int xi_a(void);
int sh_ang(void);
int sum(int ,int );
const int MIN =-1000;
const int MAX =1000;

int main(void)
{
int xia,shang;
double ji;
printf("请输入下限(0为限制退出):");
xia=xi_a();
printf("请输入上限(0为限制退出):");
shang=sh_ang();
while(xia!=0 && shang!=0)
{
ji=sum(xia,shang);
}
printf("从%d到%d的值是:%g",xia,shang,ji);

return 0;
}

int xia(void)
{
int xia;
while(scanf("%d",&xia)!=1)
{
if(xia > MIN)
return xia;
else
printf("输入有误");
}
}

int sh_ang(void)
{
int shang;
while(scanf("%d",&shang)!=1)
{
if(shang < MAX)
return shang;
else
printf("您输入有误:\n");
}
}

//这个是我自己写的一段程序目的是求阶乘值,如果输

#include<stdio.h>

int xiaxian(void);
int shangxian(void);
int sum(int ,int );
const int MIN =-1000;
const int MAX =1000;

int main(void)
{
int xia,shang;
double ji;
printf("请输入下限(0为限制退出):");
xia=xiaxian();
printf("请输入上限(0为限制退出):");
shang=shangxian();
while(xia!=0 && shang!=0)
{
ji=sum(xia,shang);
}
printf("从%d到%d的值是:%g",xia,shang,ji);

return 0;
}

int xiaxian(void)
{
int xia;
while(scanf("%d",&xia)!=1)
{
if(xia < MIN)
{
printf("输入有误");
xia = 0;
}
}
return xia;
}

int shangxian(void)
{
int shang;
while(scanf("%d",&shang)!=1)
{
if(shang > MAX)
{
shang = 0;
printf("您输入有误:\n");
}