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How to escape the % (percent) sign in C's printf?
...e:
printf("hello%%");
Escaping '%' sign is only for printf. If you do:
char a[5];
strcpy(a, "%%");
printf("This is a's value: %s\n", a);
It will print: This is a's value: %%
share
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improve th...
When should static_cast, dynamic_cast, const_cast and reinterpret_cast be used?
......
}
}
const_cast :
// *Passwd declared as a const
const unsigned char *Passwd
// on some situation it require to remove its constness
const_cast<unsigned char*>(Passwd)
reinterpret_cast :
typedef unsigned short uint16;
// Read Bytes returns that 2 bytes got read.
bool ByteBu...
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...
可重入函数、不可重入函数及线程安全 - C/C++ - 清泛网 - 专注C/C++及内核技术
...elset
tcsetattr
cfsetospeed
geteuid
pselect
sigemptyset
tcsetpgrp
chdir
getgid
raise
sigfillset
time
chmod
getgroups
read
sigismember
timer_getoverrun
...
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 I filter ForeignKey choices in a Django ModelForm?
...tions = super(FrontEndAdmin, self).get_actions(request)
if 'delete_selected' in actions:
del actions['delete_selected']
return actions
prevents delete permission
def has_delete_permission(self, request, obj=None):
return False
filters objects that can be ...
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"...
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...
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. ...