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How to track down a “double free or corruption” error
...
If you're using glibc, you can set the MALLOC_CHECK_ environment variable to 2, this will cause glibc to use an error tolerant version of malloc, which will cause your program to abort at the point where the double free is done.
You can set this from gdb by using the s...
How does the main() method work in C?
... be handled. */
extern int main(int argc, char **argv, char **envp);
void __start(void)
{
/* This is the real startup function for the executable.
It performs a bunch of library initialization. */
/* ... */
/* And then: */
exit(main(argc_from_somewhere, argv_from_somewhere, envp_from...
Stop “developer tools access needs to take control of another process for debugging to continue” ale
...ict>
- <key>group</key>
- <string>_developer</string>
<key>shared</key>
<true/>
- <key>timeout</key>
- <integer>36000</integer>
+ <key>k-of-n</key&g...
How to redirect 404 errors to a page in ExpressJS?
...low,
// this means that Express will attempt
// to match & call routes _before_ continuing
// on, at which point we assume it's a 404 because
// no route has handled the request.
app.use(app.router);
// Since this is the last non-error-handling
// middleware use()d, we assume 404, as nothing e...
How to use if - else structure in a batch file?
...at least was) DOS!
@echo off
set one=1
set two=2
REM Example 1
IF %one%_%two%==1_1 (
echo Example 1 fails
) ELSE IF %one%_%two%==1_2 (
echo Example 1 works correctly
) ELSE (
echo Example 1 fails
)
REM Example 2
set test1result=0
set test2result=0
if %one%==1 if %two%==1 set test1re...
Cleaner way to update nested structures
...ss, and an address in a person:
val addressZipCodeLens = Lens(
get = (_: Address).zipCode,
set = (addr: Address, zipCode: Int) => addr.copy(zipCode = zipCode))
val personAddressLens = Lens(
get = (_: Person).address,
set = (p: Person, addr: Address) => p.copy(address = addr)...
Include all existing fields and add new fields to document
...s the new fields.
db.collection.aggregate([
{ "$addFields": { "custom_field": "$obj.obj_field1" } }
])
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Can you find all classes in a package using reflection?
...0, file.getName().length() - 6)));
}
}
return classes;
}
__________
1 This method was taken originally from http://snippets.dzone.com/posts/show/4831, which was archived by the Internet Archive, as linked to now. The snippet is also available at https://dzone.com/articles/get-all-c...
Convert a row of a data frame to vector
...u have to be careful if your row contains a factor. Here is an example:
df_1 = data.frame(V1 = factor(11:15),
V2 = 21:25)
df_1[1,] %>% as.numeric() # you expect 11 21 but it returns
[1] 1 21
Here is another example (by default data.frame() converts characters to factors)
d...
How to get last items of a list in Python?
...
a negative index will count from the end of the list, so:
num_list[-9:]
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