大约有 40,000 项符合查询结果（耗时：0.0499秒） [XML]
C++中判断文件、目录是否存在的几种方法 - C/C++ - 清泛网 - 专注C/C++及内核技术
...
if(fh == NULL)
{
printf("%s","can not open the file");
}
三、_access
当然C中还有一种方式是直接调用c的函数库。
就是函数 int _access(const char* path,int mode);
这个函数的功能十分强大。
可以看看msdn的详细介绍
#include <io.h>
#include ...
Any way to properly pretty-print ordered dictionaries?
...well if you don't care about the order of the keys. Personally, I wish the __repr__ for OrderedDict would produce output like this but preserve the order of the keys.
– ws_e_c421
Sep 24 '15 at 15:54
...
Rails: around_* callbacks
...classes/ActiveRecord/Callbacks.html , but don't understand when the around_* callbacks are triggered in relation to before_* and after_* .
...
Why does Go have a “goto” statement
... x = x + 1
}
if x == 2 {
return z
}
x = x - 2
p = (((((x*_gamP[0]+_gamP[1])*x+_gamP[2])*x+_gamP[3])*x+_gamP[4])*x+_gamP[5])*x + _gamP[6]
q = ((((((x*_gamQ[0]+_gamQ[1])*x+_gamQ[2])*x+_gamQ[3])*x+_gamQ[4])*x+_gamQ[5])*x+_gamQ[6])*x + _gamQ[7]
return z * p / q
small:
if x == 0 ...
Getting the name of a child class in the parent class (static context)
...ot possible. in php4 you could implement a terrible hack (examine the debug_backtrace()) but that method does not work in PHP5. references:
30423
37684
34421
edit: an example of late static binding in PHP 5.3 (mentioned in comments). note there are potential problems in it's current implementat...
Delete a key from a MongoDB document using Mongoose
...de-mongodb-native driver. Each model has a collection object that contains all the methods that node-mongodb-native offers. So you can do the action in question by this:
User.collection.update({_id: user._id}, {$unset: {field: 1 }});
Since version 2.0 you can do:
User.update({_id: user._id}, {$u...
Program only crashes as release build — how to debug?
I've got a "Schroedinger's Cat" type of problem here -- my program (actually the test suite for my program, but a program nonetheless) is crashing, but only when built in release mode, and only when launched from the command line. Through caveman debugging (ie, nasty printf() messages all over the ...
Renaming columns in pandas
...UMNS
Use the df.rename() function and refer the columns to be renamed. Not all the columns have to be renamed:
df = df.rename(columns={'oldName1': 'newName1', 'oldName2': 'newName2'})
# Or rename the existing DataFrame (rather than creating a copy)
df.rename(columns={'oldName1': 'newName1', 'oldNam...
C99 stdint.h header and MS Visual Studio
... Without this header I have no definitions for useful types such as uint32_t, etc.
7 Answers
...
Is it safe to parse a /proc/ file?
.../proc/mounts was a consistent snapshot.
For example:
/proc/uptime is totally atomic, as someone mentioned in another answer -- but only since Linux 2.6.30, which is less than two years old. So even this tiny, trivial file was subject to a race condition until then, and still is in most enterpris...