View Compilation Error

0_0_38775016_3905.cpp: In function 'int read()':
0_0_38775016_3905.cpp:9:16: error: 'isdigit' was not declared in this scope
    9 |         for (;!isdigit(ch);ch=getchar());
      |                ^~~~~~~
0_0_38775016_3905.cpp:10:15: error: 'isdigit' was not declared in this scope
   10 |         for (;isdigit(ch);ch=getchar())
      |               ^~~~~~~