#include <iostream>
#include <cstring>
#define n 100
using namespace std;
int cnt = 0;
int main() {
char src[] = "Hello World";
char dst[20];
strncpy(dst, src, sizeof(dst));
printf(":%zu:", strlen(dst));
memcpy(dst, src, 5);
printf(":%zu:", strlen(dst));
strncpy(dst, src,5);
printf(":%zu:", strlen(dst));
return 0;
}
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