双printf格式...... [英] Double printf format...

问题描述

在下面的程序中


#include< stdio.h>

int main（）

{

int id = 123，io = 0123，ih = 0x123;

long ld = 1234567L，lo = 01234567l，lh = 0X1234567L;

float f = 123.456f;

double d = 01234.56789L;


printf（" id =％d \ t％o \ t％x \ nio =％d \ t％\\\ t％x \ nhh =％d \ t％O \％x \ n"，

id，id，id，io， io，io，ih，ih，ih）;

printf（" ld =％ld \ t％lo \ t％lx \ nlo =％ld \ t％lo \ t％lx \ nlh =％ld \ t％lo \ t％l \ n"，

ld，ld，ld，lo，lo，lo，lh，lh，lh） ;

printf（" f =％lf \ t％le \ t％lg \ n =％lf \ t％lE \ t％lG \ n，f， f，f，d，d，d）;

返回0;

}


输出得到：

id = 123 173 7b

io = 83 123 53

ih = 291％O 123

ld = 1234567 4553207 12d687

lo = 3 42391 1234567 53977

lh = 19088743 110642547 1234567

f = 123.456001 1.234560e + 02 123.456

d = 1234.567890 1.234568E + 03 1234.57


为什么第3行中有％O而不是预期的八进制o / p？

并且对于d而言，最后一个o / p是1234.57。但％g是％lf或％le

对吗？所以如果它是％lf那么为什么它是1234.57而不是1234.56789？


谢谢

in program below

#include <stdio.h>
int main()
{
int id = 123, io = 0123, ih = 0x123;
long ld = 1234567L, lo = 01234567l, lh = 0X1234567L;
float f = 123.456f;
double d = 01234.56789L;

printf("id = %d\t%o\t%x\nio = %d\t%o\t%x\nih = %d\t%O\t%X\n",
id, id, id, io, io, io, ih, ih, ih);
printf("ld = %ld\t%lo\t%lx\nlo = %ld\t%lo\t%lx\nlh = %ld\t%lo\t%l\n",
ld, ld, ld, lo, lo, lo, lh, lh, lh);
printf("f = %lf\t%le\t%lg\nd = %lf\t%lE\t%lG\n", f, f, f, d, d, d);
return 0;
}

the output got is:
id = 123 173 7b
io = 83 123 53
ih = 291 %O 123
ld = 1234567 4553207 12d687
lo = 342391 1234567 53977
lh = 19088743 110642547 1234567
f = 123.456001 1.234560e+02 123.456
d = 1234.567890 1.234568E+03 1234.57

why is there a %O in line 3 instead of octal o/p expected?
and in line for d the last o/p is 1234.57. but %g is either %lf or %le
right? so if it is %lf then why is it 1234.57 instead of 1234.56789?

thanks

推荐答案

naunetr写道：

naunetr wrote:

以下程序


#include< stdio.h>

int main（）

{

int id = 123，io = 0123，ih = 0x123;

long ld = 1234567L，lo = 01234567l， lh = 0X1234567L;

float f = 123.456f;

double d = 01234.56789L;


printf（" id = ％d \％％o \ t％x \ nn =％d \ t％\\\％x \ nhh =％d \ t％O \％x \ n"，

id，id，id，io，io，io，ih，ih，ih）;

printf（" ld =％ld \ t％lo \ t ％lx \ nlo =％ld \ t％lo \ t％lx \ nlh =

％ld \ t％lo \ t％l \ n"，

ld，ld，ld，lo，lo，lo，lh，lh，lh）;

printf（" f =％lf \ t％le\t％lg \ n =％lf \ t％lE \ t％lG \
"，F，F，F，d，d，

d）;返回0;

}


输出得到：

id = 123 173 7b

io = 83 123 53

ih = 291％O 123

ld = 1234567 4553207 12d687

lo = 342391 1234567 53977

lh = 19088743 110642547 1234567

f = 123.456001 1.234560e + 02 123.456

d = 1234.567890 1.234568E + 03 1234.57


为什么第3行有％O而不是预期的八进制o / p？

in program below

#include <stdio.h>
int main()
{
int id = 123, io = 0123, ih = 0x123;
long ld = 1234567L, lo = 01234567l, lh = 0X1234567L;
float f = 123.456f;
double d = 01234.56789L;

printf("id = %d\t%o\t%x\nio = %d\t%o\t%x\nih = %d\t%O\t%X\n",
id, id, id, io, io, io, ih, ih, ih);
printf("ld = %ld\t%lo\t%lx\nlo = %ld\t%lo\t%lx\nlh =
%ld\t%lo\t%l\n",
ld, ld, ld, lo, lo, lo, lh, lh, lh);
printf("f = %lf\t%le\t%lg\nd = %lf\t%lE\t%lG\n", f, f, f, d, d,
d); return 0;
}

the output got is:
id = 123 173 7b
io = 83 123 53
ih = 291 %O 123
ld = 1234567 4553207 12d687
lo = 342391 1234567 53977
lh = 19088743 110642547 1234567
f = 123.456001 1.234560e+02 123.456
d = 1234.567890 1.234568E+03 1234.57

why is there a %O in line 3 instead of octal o/p expected?

八进制输出的格式说明符是％o，而不是％O。在C情况下，

很重要。

The format specifier for octal output is %o, not %O. In C case is
important.

并且对于d，最后一个o / p是1234.57。但％g是％lf或％le

对吗？所以如果它是％lf那么为什么它是1234.57而不是1234.56789？

and in line for d the last o/p is 1234.57. but %g is either %lf or %le
right? so if it is %lf then why is it 1234.57 instead of 1234.56789?

我认为这是一个精确的问题。

I think that''s a precision issue.

naunetr写道：

[...]

naunetr wrote:
[...]

为什么有一个％O在行预期3而不是八进制o / p？

why is there a %O in line 3 instead of octal o/p expected?

因为你把它放在那里。格式字符串的相关片段是

ih =％d \ t％O \ t％X \ n


注意％O in上面的字符串？没有％O转换说明符，

和八进制转换说明符是％o

Because you put it there. The relevant fragment of the format string is
ih = %d\t%O\t%X\n

Notice the %O in the string above? There is no %O conversion specifier,
and the "octal" conversion specifier is %o

谢谢Lew。是否有一个说明符，它会在八进制前面加一个0

数？喜欢0x为％＃x？

thanks Lew. is there a specifier which will put a 0 in front off the octal
number? like 0x for %#x?

0％o怎么样？和0x％x？


[...]


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+ - ----------------------- + -------------------- + ----- ------------------ +

| Kenneth J. Brody | www.hvcomputer.com | #include |

| kenbrody / at\spamcop.net | www.fptech.com | < std_disclaimer.h |

+ ------------------------- + --------- ----------- + ----------------------- +

不要 - 邮寄给我：< mailto：Th ************* @ gmail.com>

What about "0%o" and "0x%x"?

[...]

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+-------------------------+--------------------+-----------------------+
| Kenneth J. Brody | www.hvcomputer.com | #include |
| kenbrody/at\spamcop.net | www.fptech.com | <std_disclaimer.h|
+-------------------------+--------------------+-----------------------+
Don''t e-mail me at: <mailto:Th*************@gmail.com>

文章< fr**********@registered.motzarella.org>，

naunetr< wi ************ @ roadtonowhere.invalidwrote：

In article <fr**********@registered.motzarella.org>,
naunetr <wi************@roadtonowhere.invalidwrote:

>谢谢Lew。是否有一个说明符，它会在八进制数字前面加一个0？喜欢0x为％＃x？

>thanks Lew. is there a specifier which will put a 0 in front off the octal
number? like 0x for %#x?

％＃o


C89 4.9.6.1 fprintf功能


＃结果将转换为替代形式。对于o

转换，它会增加精度以强制结果的第一个数字
为零。对于x（或X）转换，

非零结果将以0x（或0X）作为前缀。 [...]

%#o

C89 4.9.6.1 The fprintf Function

# The result is to be converted to an "alternate form." For o
conversion, it increases the precision to force the first digit
of the result to be a zero. For x (or X) conversion, a
nonzero result will have 0x (or 0X) prefixed to it. [...]

>抱歉让它与scanf混淆了！但为什么还有％F？难道不应该足够吗？

>sorry got it confused with scanf! but why is there a %F too? shouldn''t %f
be enough?

C89没有％F（但确实有％E和％G）。 ％E和％G使用

资本E代表指数代号，而不是小写e />
，但分别与％e和％g相同。 br />
-

我们观察到的怪癖和随意性迫使我们得出结论，即我们不是唯一的宇宙。 - Walter Kistler

C89 does not have %F (but does have %E and %G). %E and %G use a
capital E for the exponent signifier instead of a lower-case e
but are otherwise the same as %e and %g respectively.
--
"The quirks and arbitrariness we observe force us to the
conclusion that ours is not the only universe." -- Walter Kistler

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