Structure deep copy

c++ structure deep-copy
Kiran picture Kiran · May 23, 2011 · Viewed 14.7k times · Source

This may be a very basic question but somehow it got me tricked... when I write test code, it seems to work, but something is going wrong in production.

// Header file
#define length 100
typedef struct testStr_t {
    int a;
    char b;
    char t1[length];
    char t2[length];
} test;

void populateTest(test*);

// source file
test test1;
test test2;
populateTest(&test1);
test2 = test1;

Will test2 be a deep copy of test1? Or are there gotchas here? Does it matter if the code is compiled with a C compiler or a C++ compiler?

Answer

Chris Lutz picture Chris Lutz · May 23, 2011

Deep copies are only hindered by pointers, so your struct will be copied correctly in C. It'll work in C++ as well unless you define your own operator= that doesn't copy correctly. You only need to define operator= for types with pointers, since a shallow copy of a pointer will copy the pointer but share the data.

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