大约有 15,000 项符合查询结果（耗时：0.0162秒） [XML]
psql: FATAL: role “postgres” does not exist
I'm a postgres novice.
18 Answers
18
...
Why is there “data” and “newtype” in Haskell? [duplicate]
...pe definition is just a data definition that obeys some restrictions (e.g., only one constructor), and that due to these restrictions the runtime system can handle newtype s more efficiently. And the handling of pattern matching for undefined values is slightly different.
...
Is there a way to simulate the C++ 'friend' concept in Java?
I would like to be able to write a Java class in one package which can access non-public methods of a class in another package without having to make it a subclass of the other class. Is this possible?
...
How to change the default GCC compiler in Ubuntu?
I have installed gcc-3.3/g++-3.3 on ubuntu 11.04 which already has gcc/g++-4.4. So in my system both gcc-3.3 and 4.4 are available. I am able to call both compilers as I want. If I just call the command gcc then gcc-4.4 will get called. To call gcc-3.3, I have to use the command gcc-3.3 .
...
What is the difference between g++ and gcc?
What is the difference between g++ and gcc? Which one of them should be used for general c++ development?
10 Answers
...
UltiSnips and YouCompleteMe
... is that ultisnips doesn't work because tab is bound by ycm.
I tried putting let g:UltiSnipsExpandTrigger = "<s-tab>" so that I can trigger the snippet completion with shift-tab, but it doesn't work for some unknown reason. I could use caps as the trigger, but so far I've found no way to do ...
Difference between File.separator and slash in paths
What is the difference between using File.separator and a normal / in a Java Path-String?
14 Answers
...
Easy way to turn JavaScript array into comma-separated list?
I have a one-dimensional array of strings in JavaScript that I'd like to turn into a comma-separated list. Is there a simple way in garden-variety JavaScript (or jQuery) to turn that into a comma-separated list? (I know how to iterate through the array and build the string myself by concatenation if...
how to exclude null values in array_agg like in string_agg using postgres?
If I use array_agg to collect names, I get my names separated by commas, but in case there is a null value, that null is also taken as a name in the aggregate. For example :
...
How to represent multiple conditions in a shell if statement?
...
Classic technique (escape metacharacters):
if [ \( "$g" -eq 1 -a "$c" = "123" \) -o \( "$g" -eq 2 -a "$c" = "456" \) ]
then echo abc
else echo efg
fi
I've enclosed the references to $g in double quotes; that's good practice, in general. Strictly, the parentheses aren't neede...