缓存和两个输入语句的含义

Question

#include<stdio.h>
#include<time.h>
#include<stdlib.h>
main()
{
	int bingo,num;
	char ch='y';
	srand((unsigned)time(NULL));
	while(ch=='y')
	{
		bingo = rand()%89+10;
		printf("-------%d--------n",bingo);
		
		while(num!=bingo)
		{
			scanf("%d",&num);
			if(num>bingo)
				printf("猜大了！n");
			else if(num<bingo)
				printf("猜小了！n");
		}
		printf("猜对了！n");
		printf("请输入是否继续(y/n):");
  /*下面为何用两个scanf，用一个不行啊，难道不是先输y再换行么，这样扫描到的字符不就是换行了*/
 /*清除缓存也可以，原理是啥了*/ 

              scanf("%c",&ch);
		scanf("%c",&ch);
	}
}

Answer 1

 scanf("%d",&num);这句并没有把n读出来，下面一个scanf读的是这里的换行符

Answer 2

#include <stdio.h>
#include <stdlib.h>


void main(const int argc, const char* argv[]){

char v='y';

while(v=='y'){

printf("scan:");
scanf("%c", &v);
printf("received %dn", v);
scanf("%c", &v);

printf("received %dn", v);
}

}