How do you 'realloc' in C++?

c++ new-operator realloc delete-operator
bodacydo picture bodacydo · Aug 14, 2010 · Viewed 79.8k times · Source

How can I realloc in C++? It seems to be missing from the language - there is new and delete but not resize!

I need it because as my program reads more data, I need to reallocate the buffer to hold it. I don't think deleteing the old pointer and newing a new, bigger one, is the right option.

Answer

f0b0s picture f0b0s · Aug 14, 2010

Use ::std::vector!

Type* t = (Type*)malloc(sizeof(Type)*n) 
memset(t, 0, sizeof(Type)*m)

becomes

::std::vector<Type> t(n, 0);

Then

t = (Type*)realloc(t, sizeof(Type) * n2);

becomes

t.resize(n2);

If you want to pass pointer into function, instead of 

Foo(t)

use

Foo(&t[0])

It is absolutely correct C++ code, because vector is a smart C-array.

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