输出/输入问题 [英] Output/Input Problem
问题描述
我正在linux机器上尝试一个非常简单的程序。代码如下：
int main {
char a，b;
printf（"输入一个 ;）;
scanf（"％c"，& a）;
printf（" Enter b"）;
scanf（"％c"& b）;
printf（" b =％c \ n"，b）;
返回0;
}
当我在这里运行这是我得到的
输入：c
输入b ：b =
它只允许我输入一个字符，一旦按下
，输入第二个提示就会随b =语句和
程序退出
我做错了什么，如何更正？
scanf（"％s"& a）;
％s - 此开关允许您从控制台读取更多字符，如果
char a [..];声明是这样或作为指针。
你最好尝试阅读更多信息：尝试man scanf。
scanf（"％s"& a）;
如果我使用％s，这并不意味着我试图读取一个空的
终止字符串？我不是因为我只读了一个字符来自
stdin
在文章< 11 ***** *****************@z14g2000cwz.googlegroups .com> ;,
NO_Code< ka ****** @ gmail.com>写道：我在linux机器上尝试一个非常简单的程序。下面给出的代码
int main {
char a，b;
printf（" Enter a"）;
scanf（"％c"，& a）;
printf（" Enter b"）;
scanf（"％c"，& b）;
printf（" b =％c \ nn"，b） ;
返回0;
}
当我在这里运行这是我得到的
输入：c
输入b：b =
它只允许我只输入一个字符，一旦按下
输入第二个提示就会打印出b =语句和
程序退出
我做错了什么以及如何纠正这个？
scanf（）与％c格式元素读取*完全*一个字符。你
输入两个字符，你想要的输入和换行符
终止该行。因此在第一次scanf（）之后，你仍然在输入缓冲区中有
a字符等待第二个
scanf（）读取。
你需要知道的另一部分：
- scanf（）总是将缓冲区放在
读取之后;
- *除了*为％c和％[格式元素，scanf（）跳过前导
空格...包括可能在缓冲区中碰巧是
的换行符;
- ％c和％[格式元素不会跳过前导空格;
- ％s格式元素在行尾之前不会读取：它
跳过领先的空白然后读取直到第一个空格...
可能恰好是下一个换行符，但也可能发生
仅仅是空格或制表符。
注意这里的含义，除非你使用％c或％[
，否则scanf（）将忽略输入元素之间的行边界。 />
例如，scanf（"％） d％d，& i，& j）非常乐意阅读以下任何内容：
10 11
10 11
[tab] 10 [tab] 11
[换行] [换行] [换行] 10 11
10 [空格] [空格] [空格] [换行符] [空格] [空格] [空格] [空格] 11
-
按日期排序的结果排序是近似值。
Hi,
I am trying a very simple program on a linux machine. Code given below
int main{
char a,b;
printf("Enter a ");
scanf("%c",&a);
printf("Enter b ");
scanf("%c",&b);
printf("b= %c\n",b);
return 0;
}
when i run this here is what i get
Enter a: c
Enter b: b=
It only allows me to enter just one character and as soon as I press
enter the second prompt is printed along with the b= statement and the
program exits
What am i doing wrong and how can i correct this?
scanf("%s", &a);
%s - this switch allows you to read more characters from console if
char a[..]; is declared like that or as a pointer.
You better try to read more info: try "man scanf".
scanf("%s", &a);
If i use %s would this not mean that I am trying to read a null
terminated string? which i am not as i am reading only a character from
stdin
In article <11**********************@z14g2000cwz.googlegroups .com>,
NO_Code <ka******@gmail.com> wrote:I am trying a very simple program on a linux machine. Code given below int main{
char a,b;
printf("Enter a ");
scanf("%c",&a);
printf("Enter b ");
scanf("%c",&b);
printf("b= %c\n",b);
return 0;
} when i run this here is what i get
Enter a: c
Enter b: b=
It only allows me to enter just one character and as soon as I press
enter the second prompt is printed along with the b= statement and the
program exits
What am i doing wrong and how can i correct this?
scanf() with a %c format element reads *exactly* one character. You
are entering two characters, the input you want and the newline to
terminate the line. Thus after the first scanf(), you still have
a character in the input buffer waiting to be read by the second
scanf().
The other part of what you need to know:
- scanf() always leaves the buffer positioned right after what was
read;
- *except* for %c and %[ format elements, scanf() skips leading
whitespace... including possibly any newline that happened to be
in the buffer;
- the %c and %[ format elements do NOT skip leading whitespace;
- the %s format element does NOT read until the end of line: it
skips leading whitespace and then reads until the first whitespace...
which might happen to be the next newline, but also might happen
to be merely a space or tab.
Notice the implication here, that unless you are using %c or %[
then scanf() will ignore line boundaries between input elements.
For example, scanf("%d%d", &i, &j) is perfectly happy to read any of these:
10 11
10 11
[tab]10[tab]11
[newline][newline][newline]10 11
10[space][space][space][newline][space][space][space][space]11
--
The ordering of results sorted by date is approximate.
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