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How to determine if a string is a number with C++?
...nt way would be just to iterate over the string until you find a non-digit character. If there are any non-digit characters, you can consider the string not a number.
bool is_number(const std::string& s)
{
std::string::const_iterator it = s.begin();
while (it != s.end() && std:...
Objective-C formatting string for boolean?
...
In Objective-C, the BOOL type is just a signed char. From <objc/objc.h>:
typedef signed char BOOL;
#define YES (BOOL)1
#define NO (BOOL)0
So you can print them using the %d formatter But that will only print a 1 or a 0, not YES or NO.
Or you can...
How does grep run so fast?
... how far ahead it can skip in the input whenever it finds a
non-matching character.
GNU grep also unrolls the inner loop of Boyer-Moore, and sets up the
Boyer-Moore delta table entries in such a way that it doesn't need to
do the loop exit test at every unrolled step. The result of this ...
Is an array name a pointer?
...no storage is materialized for a separate pointer or any metadata. Given
char a[10];
what you get in memory is
+---+
a: | | a[0]
+---+
| | a[1]
+---+
| | a[2]
+---+
...
+---+
| | a[9]
+---+
The expression a refers to the entire array, but there's no obj...
Android Reading from an Input stream efficiently
... avoid creating new String objects on each append and to avoid copying the char arrays. The implementation for your case would be something like this:
BufferedReader r = new BufferedReader(new InputStreamReader(inputStream));
StringBuilder total = new StringBuilder();
for (String line; (line = r.re...
How to print time in format: 2009‐08‐10 18:17:54.811
...lt;stdio.h>
#include <time.h>
int main()
{
time_t timer;
char buffer[26];
struct tm* tm_info;
timer = time(NULL);
tm_info = localtime(&timer);
strftime(buffer, 26, "%Y-%m-%d %H:%M:%S", tm_info);
puts(buffer);
return 0;
}
For milliseconds part, have ...
What do single quotes do in C++ when used on multiple characters?
...
It's a multi-character literal. 1952805748 is 0x74657374, which decomposes as
0x74 -> 't'
0x65 -> 'e'
0x73 -> 's'
0x74 -> 't'
Edit:
C++ standard, §2.14.3/1 - Character literals
(...) An ordinary character literal that conta...
Write to .txt file?
...intf("Error opening file!\n");
exit(1);
}
/* print some text */
const char *text = "Write this to the file";
fprintf(f, "Some text: %s\n", text);
/* print integers and floats */
int i = 1;
float py = 3.1415927;
fprintf(f, "Integer: %d, float: %f\n", i, py);
/* printing single chatacters */
ch...
string c_str() vs. data()
...orm better than c_str().
strings don't necessarily have to be composed of character data, they could be composed with elements of any type. In those cases data() is more meaningful. c_str() in my opinion is only really useful when the elements of your string are character based.
Extra: In C++11 on...
Difference between angle bracket < > and double quotes “ ” while including header files in C++? [dup
...tion 6.10.2):
A preprocessing directive of the form
# include <h-char-sequence> new-line
searches a sequence of implementation-defined places for a header identified uniquely by the specified sequence between the < and > delimiters, and causes the replacement of that directi...