foo.cc: In constructor 'Charstyle::Charstyle(char*)':
foo.cc:12:9: warning: statement has no effect [-Wunused-value]
   12 |    for (i; a[i] != 0; i++)
      |         ^
foo.cc: In copy constructor 'Charstyle::Charstyle(Charstyle&)':
foo.cc:19:10: warning: statement has no effect [-Wunused-value]
   19 |     for (i; s.data[i] != 0; i++)
      |          ^
foo.cc: In function 'int main()':
foo.cc:79:9: warning: left operand of comma operator has no effect [-Wunused-value]
   79 |    for (p, j; p <= r - 1; p++, j++)
      |         ^
foo.cc:79:13: warning: right operand of comma operator has no effect [-Wunused-value]
   79 |    for (p, j; p <= r - 1; p++, j++)
      |             ^

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