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What is the effect of extern “C” in C++?
...o have a certain linkage:
extern "C" void foo(int);
extern "C"
{
void g(char);
int i;
}
If you care about the technicalities, they are listed in section 7.5 of the C++03 standard, here is a brief summary (with emphasis on extern "C"):
extern "C" is a linkage-specification
Every compiler is r...
std::string length() and size() member functions
....) and length() is to be consistent with most peoples' intuitive notion of character strings. People usually talk about a word, sentence or paragraph's length, not its size, so length() is there to make things more readable.
...
How do you use the Immediate Window in Visual Studio?
...tMessage()
"hello"
A very common way to see the value of a method is to select the method name of a class and do a ‘Add Watch’ so that you can see its current value in the Watch window. However, once again, the object needs to be instantiated and in scope for a valid value to be displayed. ...
Can a C++ enum class have methods?
... mouse_event_middle_up,
mouse_event_wheel
};
static const char* ToStr (const type::LowLevelMouseEvent::Enum& event)
{
switch (event) {
case mouse_event_unknown: return "unknown";
case mouse_event_unimplemented: return "unimplemented"...
How to implement one-to-one, one-to-many and many-to-many relationships while designing tables?
...ction table
Example queries:
-- Getting all students for a class:
SELECT s.student_id, last_name
FROM student_classes sc
INNER JOIN students s ON s.student_id = sc.student_id
WHERE sc.class_id = X
-- Getting all classes for a student:
SELECT c.class_id, name
FROM s...
Creating a daemon in Linux
...nlog(3), closelog(3)
And here is a more general function,
int
daemonize(char* name, char* path, char* outfile, char* errfile, char* infile )
{
if(!path) { path="/"; }
if(!name) { name="medaemon"; }
if(!infile) { infile="/dev/null"; }
if(!outfile) { outfile="/dev/null"; }
if(!e...
Make a float only show two decimal places
...
IN objective-c, if you are dealing with regular char arrays (instead of pointers to NSString) you could also use:
printf("%.02f", your_float_var);
OTOH, if what you want is to store that value on a char array you could use:
sprintf(your_char_ptr, "%.02f", your_float_va...
UTF-8 byte[] to String
...Look at the constructor for String
String str = new String(bytes, StandardCharsets.UTF_8);
And if you're feeling lazy, you can use the Apache Commons IO library to convert the InputStream to a String directly:
String str = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
...
How to prevent gcc optimizing some statements in C?
...ore by using the volatile type qualifier.
// Assuming pageptr is unsigned char * already...
unsigned char *pageptr = ...;
((unsigned char volatile *)pageptr)[0] = pageptr[0];
The volatile type qualifier instructs the compiler to be strict about memory stores and loads. One purpose of volatile is...
Generic TryParse
... answered Jul 1 '11 at 22:11
Charlie BrownCharlie Brown
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