How to increase struct array size at runtime

Question

I have a structure and want to increase an array size whenever SendMessage function calls

struct MQStruct {
    wchar_t *serviceName; 
    int durability; 
    int msgType; 
    int msgHeader; 
    wchar_t *msgId; 
    wchar_t *payload; 
    int payloadSize; 
    int ttl; 
    int priority;
}MQStructObj[1];


int SendMessage(wchar_t *serviceName, int durability, int msgType, int msgHeader, wchar_t *msgId, wchar_t *payload, int payloadSize, int ttl, int priority) {

//Want to add one more array object and also preserve data of previous
MQStructObj[MAX+1]

return 0;
}

Use a std::vector.

R. Martinho Fernandes
– R. Martinho Fernandes

2013-01-15 09:59:02 +00:00
Commented Jan 15, 2013 at 9:59 — R. Martinho Fernandes
– R. Martinho Fernandes, Commented Jan 15, 2013 at 9:59
This looks like a C question, is it?

Karthik T
– Karthik T

2013-01-15 10:00:02 +00:00
Commented Jan 15, 2013 at 10:00 — Karthik T
– Karthik T, Commented Jan 15, 2013 at 10:00
and std::wstring instead of wchar_t*.

hmjd
– hmjd

2013-01-15 10:00:05 +00:00
Commented Jan 15, 2013 at 10:00 — hmjd
– hmjd, Commented Jan 15, 2013 at 10:00

unwind · Accepted Answer · 2013-01-15 10:29:52Z

2

In C you will have to deal with dynamic memory (i.e allocate the array using malloc(), then take care to call free() when you stop using it etc.) yourself, and possibly use realloc() to grow an allocation.

In C++ the problem is already solved for you and you have std::vector. You may call push_back to add elements dynamically to it.

edited Jan 15, 2013 at 10:29

unwind

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answered Jan 15, 2013 at 10:00

Ivaylo Strandjev

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4 Comments

hmjd Over a year ago

realloc(), not reallocate() and malloc(), not alloc().

kmkaplan Over a year ago

And this is C and C++, not c or c++.

Ivaylo Strandjev Over a year ago

@kmkaplan that is why I answered what are the OP's options in either case. If there is way to improve the answer please say so and I will try to do it.

kmkaplan Over a year ago

@IvayloStrandjev Sorry, I must have been unclear. I mean that the typography of the names C and C++ is wrong in your answer. You write them in lower case and with code-like font instead of upper case and normal font. You wrote c where it is supposed to be C and c++ instead of C++. Just a minor nitpick anyways.

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