重新定义fprintf以进行调试 [英] Redefine fprintf for debugging purposes
问题描述
我想重新定义fprintf以进行调试。那就是我想要那个
所有输出到stdout的输出应该记录在
文件中。
我试过像
#define fprintf（x，y，z）my_fprintf（x，y，z）
和编译器给出了大约100个错误。任何人都可以帮我这个。
我甚至尝试使用可变参数宏，但它似乎太复杂了。
任何人都可以帮助这样的定义。
< br $>
谢谢和问候，
Prayag Narula
Prayag Narula写道：
我想重新定义fprintf以进行调试。那就是我想要那个
所有输出到stdout的输出应该记录在
文件中。
< snip>
您无法轻松重新定义标准库函数和符号。 fprintf
采用FILE *参数。为什么你觉得必须是stdout。只需传递它
a FILE *设置为一个文件，大概是由fopen打开的。
FILE * log;
if（（ log = fopen（" filename"，" a"））== NULL）{deal_with_error（）; }
/ * ... * /
if（fprintf（log，" format string"，...）< 0）{deal_with_error（）; }
7月23日下午1:23，Prayag Narula< prayag.nar ... @ gmail.comwrote：
#define fprintf（x，y，z）my_fprintf（x，y，z）
如果fprintf和amp;之间有空格（x，y，z）可能是这些错误的原因
。你需要没有空格fprintf（x，y，z）。
更好的是＃define fprintf my_fprintf"如果xyz保持不变
我觉得这是不太可能的，因为你会用你的文件指针替换
stdout。
我觉得在你的场景中使用variadic宏更好，因为fprintf
有可变参数。我要感谢你向我介绍这个
概念，因为很长一段时间都在寻找这样的东西.. :)
< blockquote>
" Prayag Narula" < pr *********** @ gmail.comwrote in message
news：11 ******************* ***@i38g2000prf.googlegr oups.com ...
我想重新定义fprintf进行调试目的。那就是我想要那个
所有输出到stdout的输出应该记录在
文件中。
我试过像
#define fprintf（x，y，z）my_fprintf（x，y，z）
和编译器给出的100个错误。任何人都可以帮我这个。
我甚至尝试使用可变参数宏，但它似乎太复杂了。
任何人都可以帮助这样的定义。
如果你对stdout的所有打印都是用：
fprintf（stdout，...）;
（即，使用fprintf而不是printf）
那么它真的很简单：
#ifdef DEBUG
#define OUTFILE myfile
#else
#define OUTFILE stdout
#endif
然后所有打印语句变为：
fprintf（OUTFILE，...）;
确保在
执行任何fprintf语句之前成功打开myfile。
-
Fred L. Kleinschmidt
波音助理技术研究员
航空稳定性和控制计算
Hi,
I want to redefine fprintf for debugging purposes. That is I want that
all the output that is going to the stdout should be logged in a
file.
I tried something like
#define fprintf (x,y,z) my_fprintf(x,y,z)
and the compiler gave about 100 errors. Can anyone help me with this.
I have even tried using variadic macros but it seems too complicated.
Can anyone just help with such a defination.
Thanks and Regards,
Prayag Narula
Prayag Narula wrote:
Hi,
I want to redefine fprintf for debugging purposes. That is I want that
all the output that is going to the stdout should be logged in a
file.<snip>
You cannot portably redefine Standard library functions and symbols. fprintf
takes a FILE * argument. Why do you feel that must be stdout. Just pass it
a FILE * set to a file, presumably opened by fopen.
FILE *log;
if((log = fopen("filename", "a")) == NULL) { deal_with_error(); }
/* ... */
if(fprintf(log, "format string", ...) < 0) { deal_with_error(); }
On Jul 23, 1:23 pm, Prayag Narula <prayag.nar...@gmail.comwrote:
#define fprintf (x,y,z) my_fprintf(x,y,z)
If there is space between fprintf & (x,y,z) that could be the reason
for those errors. You need to have it without space "fprintf(x,y,z)".
Even better would be "#define fprintf my_fprintf" if x y z remain same
which I think is highly unlikely as u would be changing replacing
stdout with your file pointer.
I feel using variadic macros fit better in your scenario as fprintf
has variable arguments. I would to thank you to introduce me this
concept as was looking for something like this for a long time.. :)
"Prayag Narula" <pr***********@gmail.comwrote in message
news:11**********************@i38g2000prf.googlegr oups.com...Hi,
I want to redefine fprintf for debugging purposes. That is I want that
all the output that is going to the stdout should be logged in a
file.
I tried something like
#define fprintf (x,y,z) my_fprintf(x,y,z)
and the compiler gave about 100 errors. Can anyone help me with this.
I have even tried using variadic macros but it seems too complicated.
Can anyone just help with such a defination.
If all of your printing to stdout is done with:
fprintf( stdout, ...);
(that is, using fprintf rather than printf)
then it is really easy:
#ifdef DEBUG
#define OUTFILE myfile
#else
#define OUTFILE stdout
#endif
Then all print statements become:
fprintf( OUTFILE, ... );
Make sure you successfully open myfile before
any of the fprintf statements are executed.
--
Fred L. Kleinschmidt
Boeing Associate Technical Fellow
Aero Stability and Controls Computing
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