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Is std::vector so much slower than plain arrays?
... created. What happens if we change Pixel to:
struct Pixel
{
unsigned char r, g, b;
};
Result: about 10% faster. Still slower than an array. Hm.
# ./vector
UseArray completed in 3.239 seconds
UseVector completed in 5.567 seconds
Idea #4 - Use iterator instead of loop index
How about usin...
How to concatenate a std::string and an int?
...tm;
sstm << name << age;
result = sstm.str();
// 7. with itoa
char numstr[21]; // enough to hold all numbers up to 64-bits
result = name + itoa(age, numstr, 10);
// 8. with sprintf
char numstr[21]; // enough to hold all numbers up to 64-bits
sprintf(numstr, "%d", age);
result = name + ...
How do pointer to pointers work in C?
...his case, if this is the only occurrence of "hello" in memory then,
const char *c = "hello";
... defines c to be a pointer to the (read-only) string "hello", and thus contains the value 63. c must itself be stored somewhere: in the example above at location 58. Of course we can not only point to ...
C libcurl get output into a string
...
#include <string.h>
#include <curl/curl.h>
struct string {
char *ptr;
size_t len;
};
void init_string(struct string *s) {
s->len = 0;
s->ptr = malloc(s->len+1);
if (s->ptr == NULL) {
fprintf(stderr, "malloc() failed\n");
exit(EXIT_FAILURE);
}
s->pt...
warning: implicit declaration of function
...er has not seen the declaration. */
return 0;
}
int fun(int x, char *p)
{
/* ... */
}
You need to declare your function before main, like this, either directly or in a header:
int fun(int x, char *p);
sha...
Concatenate two string literals
...tring literals using +, it is because a string literal is just an array of characters (a const char [N] where N is the length of the string plus one, for the null terminator). When you use an array in most contexts, it is converted into a pointer to its initial element.
So, when you try to do "H...
Where in memory are my variables stored in C?
...---> heap also stack (the teacher was trying to trick you)
pointers(ex: char *arr, int *arr) -------> heap data or stack, depending on the context. C lets you declare a global or a static pointer, in which case the pointer itself would end up in the data segment.
dynamically allocated space(us...
How to get the position of a character in Python?
How can I get the position of a character inside a string in python?
9 Answers
9
...
Get Substring - everything before certain char
I'm trying to figure out the best way to get everything before the - character in a string. Some example strings are below. The length of the string before - varies and can be any length
...
What is the best way to find the users home directory in Java?
... = null;
int dwFlags = Shell32.SHGFP_TYPE_CURRENT;
char[] pszPath = new char[Shell32.MAX_PATH];
int hResult = Shell32.INSTANCE.SHGetFolderPath(hwndOwner, nFolder,
hToken, dwFlags, pszPath);
if (Shell32.S_OK == hResult) {
...