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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...
Hash function that produces short hashes?
...ay of encryption that can take a string of any length and produce a sub-10-character hash? I want to produce reasonably unique ID's but based on message contents, rather than randomly.
...
How do I iterate over the words of a string?
...or>
template <typename Out>
void split(const std::string &s, char delim, Out result) {
std::istringstream iss(s);
std::string item;
while (std::getline(iss, item, delim)) {
*result++ = item;
}
}
std::vector<std::string> split(const std::string &s, cha...
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...
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: %%
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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.
...
What would be the Unicode character for big bullet in the middle of the character?
... These links contain some more info like HTML entities for these four characters: fileformat.info/info/unicode/char/25cf fileformat.info/info/unicode/char/26ab fileformat.info/info/unicode/char/2b24 fileformat.info/info/unicode/char/1f311
– D Coetzee
Aug 3...
C compile error: “Variable-sized object may not be initialized”
...
This gives error:
int len;
scanf("%d",&len);
char str[len]="";
This also gives error:
int len=5;
char str[len]="";
But this works fine:
int len=5;
char str[len]; //so the problem lies with assignment not declaration
You need to put value in the following way:
s...
Generic TryParse
... answered Jul 1 '11 at 22:11
Charlie BrownCharlie Brown
79755 silver badges22 bronze badges
...
How does database indexing work? [closed]
... Size on disk
id (Primary key) Unsigned INT 4 bytes
firstName Char(50) 50 bytes
lastName Char(50) 50 bytes
emailAddress Char(100) 100 bytes
Note: char was used in place of varchar to allow for an accurate size on disk value.
This sample database contains ...