How to resize array in C

Question

I need to do the equivalent of the following C  code in C    Array Resize ref A  A Length - 1     How to achieve this in C

User · Answer

You cannot resize array  you can only allocate new one  with a bigger size  and copy old array s contents  If you don t want to use std  vector  for some reason  here is the code to it   int size   10  int  arr   new int size    void resize         size t newSize   size   2      int  newArr   new int newSize        memcpy  newArr  arr  size   sizeof int          size   newSize      delete    arr      arr   newArr      code is from here http   www cplusplus com forum general 11111

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You can do smth like this for 1D arrays  Here we use int  amp  because we want our pointer to be changeable   include lt algorithm gt     for copy  void resize int  amp  a  size t amp  n       size t new n   2   n     int  new a   new int new n      copy a  a   n  new a      delete   a     a   new a     n   new n     For 2D arrays   include lt algorithm gt     for copy  void resize int   amp  a  size t amp  n       size t new n   2   n  i   0     int   new a   new int   new n      for  i   0  i    new n    i         new a i    new int 100      for  i   0  i    n    i              copy a i   a i    100  new a i           delete   a i           delete   a     a   new a     n   new n     Invoking of 1D array  void myfn int  amp  a  size t amp  n          do smth    resize a  n      Invoking of 2D array  void myfn int   amp  a  size t amp  n          do smth    resize a  n

User · Answer

You cannot do that  see this question s answers  You may use std vector instead

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Use std  vector or Write your own method  Allocate chunk of memory using new  with that memory you can expand till the limit of memory chunk

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Raw arrays aren t resizable in C     You should be using something like a Vector class which does allow resizing    std  vector allows you to resize it as well as allowing dynamic resizing when you add elements  often making the manual resizing unnecessary for adding

User · Answer

The size of an array is static in C    You cannot dynamically resize it  That s what std  vector is for    std  vector lt int gt  v     size of the vector starts at 0  v push back 10      v now has 1 element v push back 20      v now has 2 elements v push back 30      v now has 3 elements  v pop back       removes the 30 and resizes v to 2  v resize v size   - 1      resizes v to 1

[c++] How to resize array in C++?

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