java - What char variable really is? -

both statements valid:

char c1 = 'a'; char c2 = 97; 

now, if add char variable, lets say:

char c3 = 10; 

and sum c2 , c3 so:

int sum = c2 + c3 

i not compile error , why that? , why need ever sum 2 chars?

thanks

each character represented type 'char' in java mapped number in ascii table. when add values adding operands numeric equivalent (the char types cast int) x (120 ascii val) - p(80 ascii val) give integer value 40.

dec  char                           dec  char     dec  char     dec  char ---------                           ---------     ---------     ----------   0  nul (null)                      32  space     64  @         96  `   1  soh (start of heading)          33  !         65          97    2  stx (start of text)             34  "         66  b         98  b   3  etx (end of text)               35  #         67  c         99  c   4  eot (end of transmission)       36  $         68  d        100  d   5  enq (enquiry)                   37  %         69  e        101  e   6  ack (acknowledge)               38  &         70  f        102  f   7  bel (bell)                      39  '         71  g        103  g   8  bs  (backspace)                 40  (         72  h        104  h   9  tab (horizontal tab)            41  )         73         105   10  lf  (nl line feed, new line)    42  *         74  j        106  j  11  vt  (vertical tab)              43  +         75  k        107  k  12  ff  (np form feed, new page)    44  ,         76  l        108  l  13  cr  (carriage return)           45  -         77  m        109  m  14   (shift out)                 46  .         78  n        110  n  15  si  (shift in)                  47  /         79  o        111  o  16  dle (data link escape)          48  0         80  p        112  p  17  dc1 (device control 1)          49  1         81  q        113  q  18  dc2 (device control 2)          50  2         82  r        114  r  19  dc3 (device control 3)          51  3         83  s        115  s  20  dc4 (device control 4)          52  4         84  t        116  t  21  nak (negative acknowledge)      53  5         85  u        117  u  22  syn (synchronous idle)          54  6         86  v        118  v  23  etb (end of trans. block)       55  7         87  w        119  w  24  can (cancel)                    56  8         88  x        120  x  25  em  (end of medium)             57  9         89  y        121  y  26  sub (substitute)                58  :         90  z        122  z  27  esc (escape)                    59  ;         91  [        123  {  28  fs  (file separator)            60  <         92  \        124  |  29  gs  (group separator)           61  =         93  ]        125  }  30  rs  (record separator)          62  >         94  ^        126  ~  31   (unit separator)            63  ?         95  _        127  del 

https://www.cs.cmu.edu/~pattis/15-1xx/common/handouts/ascii.html

this prints numbers 32-128 , associated char:

for (int c=32; c<128; c++)  {      system.out.println("ascii #: " + c + " char" + ": " + (char)c); }