c语言 while循环 每次循环7次之后就停在那里进行不下去了
下面的程序就是一个猜数字的游戏，在0-100间的数字，内定一个数字， 然后猜数字，通过交互输入 ，程序最终通过二分法找到我们需要的正确数字。
下面的程序问题应该不是很大， 问题是 每次 只循环7次 ，也就是 输入的次数 达到7次之后，程序就停在那里了 没反应了。
程序如下：
#include<stdio.h>
int center(int start,int end);
int main(void)
{
int guess,start=0,end=100,a,x;
char judge;
printf("Please guess a integer which is between 0 and 100,after i guess ,\n "
"please enter 'y' or 'w' which means right or wrong. if i guess bigger than\n"
"the true value,please enter 'b', if samller ,enter 's'.\n");
printf("Now i start guess, i guess the integer is:\n");
scanf("%d",&guess);
fflush(stdin);
while (guess<0||guess>100)
{
printf("You enter wrong integer which is should between 0 and 100, please enter again:\n");
scanf("%d",&guess);
fflush(stdin);
}
printf("The integer i guess is %d.\n",guess);
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge=getchar();
getchar();
if(judge=='y')
printf("You are right, your guess is %d which is equal to the true value.\n",guess);
while(judge!='y')
{
switch(judge)
{
case 'b': a=guess;
guess=center(start,guess);
printf("The integer i guess is %d.\n",guess);
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge=getchar();
getchar();
if (judge=='s')
{
end=a;
}
break;
case 's': x=guess;
guess=center(guess,end);
printf("The integer i guess is %d.\n",guess);
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge=getchar();
getchar();
if(judge=='b') start=x;
break;
default: break;
}
}
printf("You are right, your guess is %d which is equal to the true value.\n",guess);
return 0;
}
int center(int start,int end)
{
int result1;
result1=(start+end)/2;
return result1;
}
例如 我们假定 真实的数字是 38， 初次输入猜测的数字是 52，
运行的结果如下图：
请问这是什么原因呢？
你运行下看看
#include<stdio.h>
int center(int start, int end);
int main(void)
{
int guess, start = 0, end = 100, a, x;
char judge;
printf("Please guess a integer which is between 0 and 100,after i guess ,\n "
"please enter 'y' or 'w' which means right or wrong. if i guess bigger than\n"
"the true value,please enter 'b', if samller ,enter 's'.\n");
printf("Now i start guess, i guess the integer is:\n");
scanf("%d", &guess);
fflush(stdin);
while (guess < 0 || guess>100)
{
printf("You enter wrong integer which is should between 0 and 100, please enter again:\n");
scanf("%d", &guess);
fflush(stdin);
}
getchar();
printf("The integer i guess is %d.\n", guess);
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge = getchar();
getchar();
if (judge == 'y')
printf("You are right, your guess is %d which is equal to the true value.\n", guess);
while (judge != 'y')
{
switch (judge)
{
case 'b': a = guess;
guess = center(start, guess);
printf("The integer i guess is %d.\n", guess);
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge = getchar();
getchar();
if (judge == 's')
{
end = a;
}
break;
case 's': x = guess;
guess = center(guess, end);
printf("The integer i guess is %d.\n", guess);
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge = getchar();
getchar();
if (judge == 'b') start = x;
break;
default: break;
}
}
printf("You are right, your guess is %d which is equal to the true value.\n", guess);
return 0;
}
int center(int start, int end)
{
int result1;
result1 = (start + end) / 2;
return result1;
}
你的code有bug，，如果输入的不是 b或者 s，没有异常处理，会出现你所谓的 卡住了。
其实是 进入了 default case，然后一直while-defalut-while
可能你需要删掉35，55，76，我无法看出它们的意义
你写的代码我觉得错误的点在于 swich代码块中的getchar赋予的变量值是局部变量，当你输入y时，它只会无限break；
感觉你这个代码好多，python做了一下，这个思路，你转成C语言试试。
#l,r=1,100
while True:#无限循环
m=(l+r)//2
print('请问你猜得数字是不是%d' %(m))
a=int(input('1.是，2.大了，3.小了:'))
if a==1:
print('欧耶,恭喜你答对了！')
break
elif a==2:
r=m
else:
l=m
本地没有复现你的问题，可以正常输出。
建议将fflush函数放在scanf之前
建议你加个退出条件 start>=end 就退出，因为已经猜到了。没必要一直傻傻的循环
default:
printf("Input is invalid option.\n");
printf("Pls input again:");
judge=getchar();
getchar();
break;
二分法还有问题：
case ‘b’：
if (judge=='s')
{
end=a;
}else end=guess;
case ‘c’：
if(judge=='b') start=x;
else start=guess;
加上else，更新参数
case 'b': a=guess;
guess=center(start,guess);
printf("The integer i guess is %d.\n",guess);
if(guess-start<=1)
{
judge='y';
break;
}
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge=getchar();
getchar();
if (judge=='s')
{
end=a;
}else end=guess;
break;
case 's': x=guess;
guess=center(guess,end);
printf("The integer i guess is %d.\n",guess);
if(end-guess<=1)
{
judge='y';
break;
}
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
judge=getchar();
getchar();
if(judge=='b') start=x;
else start=guess;
break;
加了自动退出机制
你的这个程序 有问题：
正确的写法应该是：
printf("Please determine if my guess is equal to the true value,and corresponding to the input 'y' 'b' 's'.\n");
getchar();
judge=getchar();
由于printf输出了一个换行符，所以需要getchar()接收下，否则你是无法judge获取b值得，之前的写法b值被丢掉了，获取了个换行符赋给了judge，
下面有关
printf("\n")里有换行的如果下面紧接着需要getchar()字符的都需要先空调用一下getchar()接收换行，然后再judge=getchar()
有用的话麻烦您采纳一下