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Why does this loop produce “warning: iteration 3u invokes undefined behavior” and output more than 4
...in seeing this code:
struct foo *s = ...;
int x = s->f;
if (!s) return ERROR;
gcc inferred that since s was deferenced in s->f; and since dereferencing a null pointer is undefined behavior then s must not be null and therefore optimizes away the if (!s) check on the next line.
The lesson ...
ActionController::InvalidAuthenticityToken
Below is an error, caused by a form in my Rails application:
24 Answers
24
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How do you determine the size of a file in C?
...struct stat definition, which was missing the variable name.
Returns -1 on error instead of 0, which would be ambiguous for an empty file. off_t is a signed type so this is possible.
If you want fsize() to print a message on error, you can use this:
#include <sys/stat.h>
#include <sys/ty...
Which Boost features overlap with C++11?
...see the list below
gamma function (tgamma), log gamma function (lgamma)
error functions (erf, erfc)
log1p, expm1
cbrt, hypot
acosh, asinh, atanh
TR1 (they are marked in the documentation if those are TR1 libraries)
Array → std::array
Bind → std::bind
Enable If → std::enable_if
Function...
Counting array elements in Python [duplicate]
...
answered Jul 17 '15 at 3:05
Evan YoungEvan Young
1777 bronze badges
...
Array.push() if does not exist?
...verywhere.
– dt192
May 30 '19 at 14:05
Thank you, saves my time.
– Mehadi Hassan
...
What is the 'dynamic' type in C# 4.0 used for?
... (like in your example with the squareroot) you give up clean compile time error checking; instead you are now getting possible runtime errors.
– Philip Daubmeier
Apr 22 '10 at 12:42
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How to save an activity state using save instance state?
...e when going through documentation. 1 vote up :)
– AZ_
Nov 26 '10 at 5:13
21
I dont think this an...
How do you find the row count for all your tables in Postgres
...vy activity, but is generally a good estimate:
SELECT schemaname,relname,n_live_tup
FROM pg_stat_user_tables
ORDER BY n_live_tup DESC;
That can also show you how many rows are dead, which is itself an interesting number to monitor.
The third way is to note that the system ANALYZE command, ...
Execute command on all files in a directory
... This is the correct way to process files. Using a for loop is error-prone due to many reasons. Also sorting can be done by using other commands such as stat and sort, which of-course dependes on what is sorting criteria.
– tuxdna
Dec 25 '13 at 8:10...