我正在用c编写一个程序，我用的是函数flushall_ 在2013年的Express express中使用它并且它一直给我错误：
Error 1 error LNK2019: unresolved external symbol _flushall_ referenced in function _main C:\Users\Naya123\Desktop\proj1\proj1\q1.obj proj1
我还尝试将代码复制到一个新项目中，我也从代码中删除了函数flushall_但仍然是相同的
代码（仅限主要代码）：
#include<stdio.h>
#include<math.h>
#include<string.h>
void main()
{
char option; int num1, num2, num3,count=0,num,base;
menue();
scanf_s("%c",&option);
while (option != 'Y' || option != 'y')
{
switch (option)
{
case 'a' :
case 'A':
printf("insert first number : "); scanf_s("%d", &num1);
printf("insert seconde number : "); scanf_s("%d", &num2);
printf("insert third number : "); scanf_s("%d", &num3);
printf("the max between these three is %d \n ", max(num1, num2, num3));
break;
case 'B' :
case 'b':
printf("insert first number : "); scanf_s("%d", &num1);
printf("insert seconde number : "); scanf_s("%d", &num2);
printf("insert third number : "); scanf_s("%d", &num3);
printf("the min \n");
//printf("the min between these three is %d \n ", min(num1, num2, num3));
break;
case 'C':
case 'c':
printf("insert number : "); scanf_s("%d", &num);
if (is_positive(num) == ERROR)
{
printf("Error back to menue \n");
break;
}
else {
printf("the oposite of the number is %d \n ", oposite(num));
break;
}
case 'D':
case 'd':
printf("insert number : "); scanf_s("%d", &num);
if (is_positive(num) == ERROR)
{
printf("Error back to menue \n");
break;
}
else {
printf("the oposite of the number is %d \n ", (is_polendrom(num)== 0) ? "the number isn't a polindrom \n" : "the number is a polindrom \n");
break;
}
case 'E':
case 'e':
printf("insert number : "); scanf_s("%d", &num);
if (is_positive(num) == ERROR)
{
printf("Error back to menue \n");
break;
}
else {
printf("insert the base: "); scanf_s("%d", &base);
printf("the number in a detcimal base is %d \n ", numByBase10(num,base));
break;
}
case 'F':
case 'f':
printf("insert number : "); scanf_s("%d", &num);
if (num < 0)
num = (make_bolindrom(-1 * num))*-1;
else num = make_bolindrom(num);
break;
case 'G':
case 'g' :
printf("DoYou Really want to quit? y/n \n");
option=getchar(); enter=flushall_();
if (option == 'Y' || option == 'y')
printf("thx for using the system ! byee \n");
else
menue();
break;
}
if (option != 'Y' || option != 'y')
{
menue();
scanf_s("%c",&option);
}
}
}