C++ basic array assignment is not working -


so have function 

f(int d[],int a[],int len){ for(int k = 0; k < len; k++) d[k] = a[k];

and if output d numbers wrong. function f called d initialised int* d = new int[100000]; in main function , a because output in function , looks ok. so... can't understand problem is... tried memcpy(d+k,a+k,sizeof(int)); , doesn't work.

your loop works perfectly. problem must somewhere else in code.

here example program copies data in 3 different ways: for loop, memcpy, , std::copy:

#include <algorithm> #include <cstring> #include <iostream> #include <iterator> void copy1(int d[], int a[], int len) { for(int k = 0; k < len; k++) d[k] = a[k]; } void copy2(int d[], int a[], int len) { std::memcpy(d, a, len*sizeof(int)); } void copy3(int d[], int a[], int len) { std::copy(a, a+len, d); } int main () { int a[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; int *d = new int[10]; std::ostream_iterator<int> out(std::cout, ","); // first, print initial values std::copy(d, d+10, out); std::cout << "\n"; // next copies , print values again copy1(d, a, 10); std::copy(d, d+10, out); std::cout << "\n"; copy2(d, a, 10); std::copy(d, d+10, out); std::cout << "\n"; copy3(d, a, 10); std::copy(d, d+10, out); std::cout << "\n"; }

the output is:

0,0,0,0,0,0,0,0,0,0, 1,2,3,4,5,6,7,8,9,10, 1,2,3,4,5,6,7,8,9,10, 1,2,3,4,5,6,7,8,9,10,

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