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How to select a single field for all documents in a MongoDB collection?
...nt such as:
db.student.find({}, {roll:1, _id:0})
The above statement will select all documents in the students collection, and the returned document will return only the roll field (and exclude the _id).
If we don't mention _id:0 the fields returned will be roll and _id. The '_id' field is always d...
How to increment a pointer address and pointer's value?
... ----------
let me give an example, this might help;
char **str;
str = (char **)malloc(sizeof(char*)*2); // allocate mem for 2 char*
str[0]=(char *)malloc(sizeof(char)*10); // allocate mem for 10 char
str[1]=(char *)malloc(sizeof(char)*10); // allocate m...
I want to remove double quotes from a String
...r goal is to replace all double quotes).
Here's how it works:
['"] is a character class, matches both single and double quotes. you can replace this with " to only match double quotes.
+: one or more quotes, chars, as defined by the preceding char-class (optional)
g: the global flag. This tells J...
Catch Ctrl-C in C
... (1)
pause();
return 0;
}
void INThandler(int sig)
{
char c;
signal(sig, SIG_IGN);
printf("OUCH, did you hit Ctrl-C?\n"
"Do you really want to quit? [y/n] ");
c = getchar();
if (c == 'y' || c == 'Y')
exit(0);
else
signa...
iterating over each character of a String in ruby 1.8.6 (each_char)
I am new to ruby and currently trying to operate on each character separately from a base String in ruby. I am using ruby 1.8.6 and would like to do something like:
...
In Java, is there a way to write a string literal without having to escape quotes?
...of resides in the Java Language Specification:
StringLiteral:
"StringCharacters"
StringCharacters:
StringCharacter
| StringCharacters StringCharacter
StringCharacter:
InputCharacter but not " or \
| EscapeSequence
As you can see a StringLiteral can just be bound by " and ca...
When do we have to use copy constructors?
...at is not sufficient. For example:
class Class {
public:
Class( const char* str );
~Class();
private:
char* stored;
};
Class::Class( const char* str )
{
stored = new char[srtlen( str ) + 1 ];
strcpy( stored, str );
}
Class::~Class()
{
delete[] stored;
}
in this case memb...
Memcached vs. Redis? [closed]
...
Use Redis if
You require selectively deleting/expiring items in the cache. (You need this)
You require the ability to query keys of a particular type. eq. 'blog1:posts:*', 'blog2:categories:xyz:posts:*'. oh yeah! this is very important. Use this to i...
C++ : why bool is 8 bits long?
... address of an object. The object doesn't have to store its own address. A char is typically 8 bits wide, enough to store any of 256 characters, but each char also has an address defined by where in memory it is located. That is why you can create a pointer to a char.
– jalf
...
How can I transform between the two styles of public key format, one “BEGIN RSA PUBLIC KEY”, the oth
...le, after all). If I recall properly, the generic EVP_PKEY structure has a union for all the key types, with each key type having its own special set of values (the helpfully named g, w, q, and other consonants).
In conclusion, I note there was a complaint regarding programming & development; n...