View Compilation Error

0_0_24639780_11093.cpp: In function 'void read(T&)':
0_0_24639780_11093.cpp:16:17: error: '_ch' was not declared in this scope
  while(!isdigit(_ch=getchar()));
                 ^
0_0_24639780_11093.cpp:17:8: error: '_ch' was not declared in this scope
  for(a=_ch-'0';isdigit(_ch=getchar());a=(a<<3)+(a<<1)+_ch-'0');
        ^