怎的输入密码时显示*号

怎样输入密码时显示*号啊
int choice;
char code[10]="teacher",c[10];                   //删除时候使用
    int count;
    FILE*fp;
    fp=fopen("D:\\学生.txt","rb");
if(fp==NULL)
{
printf("file cannot be opened");
exit(1);
}
count=0;
while(fread(s,sizeof(student),1,fp)==1)          //读出文件中共有结构体数
count++;
//printf("%d",count);
fclose(fp);
    printf("请输入密码：");                          //教师操作密码
        scanf("%s",c);
        if(strcmp(c,code)==0)



{do
{
        menuInput1();

      {printf("请选择:\n");
      scanf("%d",&choice);}
怎样显示出来的时候是*
------解决方案--------------------

#include <conio.h>

#include <stdio.h>

char pw[40];

int i,ch;

FILE *f;

void main() {

    cprintf("\r\nPassword:");

    i=0;pw[i]=0;

    while (1) {

        ch=getch();

        if (ch==13 
------解决方案--------------------
 i>=39) break;

        switch (ch) {

        case 27:

            cprintf("\rPassword: %40s"," ");

            cprintf("\rPassword: ");

            i=0;pw[i]=0;

            break;

        case 8:

            if (i>0) {

                i--;

                pw[i]=0;

                cprintf("\b \b");

            }

            break;

        default:

            pw[i]=ch;

            i++;

            pw[i]=0;

            cprintf("*");