View Compilation Error

0_0_31415170_30963.cpp: In function 'void rd(__int128&)':
0_0_31415170_30963.cpp:9:22: error: 'isdigit' was not declared in this scope
     while(!isdigit(ch)) {w|=ch=='-';ch=getchar();}
                      ^
0_0_31415170_30963.cpp:10:21: error: 'isdigit' was not declared in this scope
     while(isdigit(ch)) X=(X<<3)+(X<<1)+(ch^48),ch=getchar();
                     ^