How can I declare and define multiple variables in one line using C

Question

I always though that if I declare these three variables that they will all have the value 0  int column  row  index   0    But I find that only index equals zero  amp  the others are junk like 844553  amp  2423445   How can I initialise all these variables to zero without declaring each variable on a new line

User · Answer

int column 0   row 0   index 0     Note that this form will work with custom types too  especially when their constructors take more than one argument

User · Answer

As of C  17  you can use Structured Bindings   include  lt iostream gt   include  lt tuple gt   int main           auto  hello  world    std  make tuple  quot Hello  quot    quot world  quot        std  cout  lt  lt  hello  lt  lt  world  lt  lt  std  endl      return 0     Demo

User · Answer

Possible approaches    Initialize all local variables with zero   Have an array  memset or  0  the array   Make it global or static   Put them in struct  and memset or have a constructor that would initialize them to zero

User · Answer

template  lt typename    A gt  constexpr auto assign A amp     a  noexcept     return   amp   auto amp  amp     v  noexcept noexcept        a   std  forward lt decltype v  gt  v                         a   std  forward lt decltype v  gt  v                    int column  row  index   assign column  row  index  0  0  0

User · Answer

When you declare a variable without initializing it  a random number from memory is selected and the variable is initialized to that value

User · Answer

int column   0  row   0  index   0

User · Answer

When you declare   int column  row  index   0    Only index is set to zero   However you can do the following   int column  row  index  column   index   row   0    But personally I prefer the following which has been pointed out  It s a more readable form in my view   int column   0  row   0  index   0    or  int column   0  int row   0  int index   0

User · Answer

I wouldn t recommend this  but if you re really into it being one line and only writing 0 once  you can also do this   int row  column  index   row   column   0

User · Answer

If you declare one variable object per line not only does it solve this problem  but it makes the code clearer and prevents silly mistakes when declaring pointers   To directly answer your question though  you have to initialize each variable to 0 explicitly  int a   0  b   0  c   0

User · Answer

As others have mentioned  from C  17 onwards you can make use of structured bindings for multiple variable assignments   Combining this with std  array and template argument deduction we can write a function that assigns a value to an arbitrary number of variables without repeating the type or value    include  lt iostream gt   include  lt array gt   template  lt int N  typename T gt  auto assign T value        std  array lt T  N gt  out      out fill value       return out     int main         auto  a  b  c    assign lt 3 gt  1        for  const auto amp  v    a  b  c                 std  cout  lt  lt  v  lt  lt  std  endl             return 0      Demo

User · Answer

As  Josh said  the correct answer is   int column   0      row   0      index   0    You ll need to watch out for the same thing with pointers  This   int  a  b  c    Is equivalent to   int  a  int b  int c

[c++] How can I declare and define multiple variables in one line using C++?

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