fast array copy c++

[fr33host]

Dear developers,
I have a question. Is there a faster array copy than a for loop. What
would you suggest for this code sample?

void get(char* src, char* dest, int i) {
for (int j = 0; j < recordLen; j++, i++) {
dest[j] = src;
}
}

Thank you for your answers.

 

[utab]

Dear developers,
I have a question. Is there a faster array copy than a for loop. What
would you suggest for this code sample?

void get(char* src, char* dest, int i) {
for (int j = 0; j < recordLen; j++, i++) {
dest[j] = src;
}
}

Thank you for int main()

An option:

std::string source("COPY THIS STRING WITH STL COPY");
std::string dest;
copy(source.begin(),source.end(),back_inserter(dest));
std::cout << dest << std::endl;
return 0;

 

[Zeppe]

Dear developers,
I have a question. Is there a faster array copy than a for loop. What
would you suggest for this code sample?

void get(char* src, char* dest, int i) {
for (int j = 0; j < recordLen; j++, i++) {
dest[j] = src;
}
}

Thank you for int main()

An option:

std::string source("COPY THIS STRING WITH STL COPY");
std::string dest;
copy(source.begin(),source.end(),back_inserter(dest));
std::cout << dest << std::endl;
return 0;

this is slower because it doesn't take advantage of knowing the size of
the destination in advance.

An STL implementation of the for cycle is:

std::fill(src, src + recordLen, dest);

Best wishes,

Zeppe

 

[utab]

Dear developers,
I have a question. Is there a faster array copy than a for loop. What
would you suggest for this code sample?

void get(char* src, char* dest, int i) {
for (int j = 0; j < recordLen; j++, i++) {
dest[j] = src;
}
}

Thank you for int main()

An option:

std::string source("COPY THIS STRING WITH STL COPY");
std::string dest;
copy(source.begin(),source.end(),back_inserter(dest));
std::cout << dest << std::endl;
return 0;

this is slower because it doesn't take advantage of knowing the size of
the destination in advance.

An STL implementation of the for cycle is:

std::fill(src, src + recordLen, dest);

Best wishes,

Zeppe

Thx for the reminder!

 

[Matthias Pfeifer]

this is slower because it doesn't take advantage of knowing the size of
the destination in advance.

An STL implementation of the for cycle is:

std::fill(src, src + recordLen, dest);

I am also interested in an STL implementation of the mentioned for cycle

void get(char* src, char* dest, int i) {
for (int j = 0; j < recordLen; j++, i++) {
dest[j] = src;
}
}

and that takes advantage of knowing the size of the destination in
advance, but std::fill does not seem to do the trick for me. std::fill
stores the value dest at [src, src+recordLen). Or am I mistaken?

Matthias

 

[Frank Birbacher]

Hi!

this is slower because it doesn't take advantage of knowing the size of
the destination in advance.

Well:
std::string dest(source.begin(), source.end());

Or just:
std::string dest = source;

(which sometimes ends up to do no copying at all)


Regards, Frank