设变量已正确定义,选项( )与以下等价。 switch (ch){ case '-': minus++; break; case '0' : case '1' : case '2' : case '3' : case '4' : case '5' : case '6' : case '7' : case '8' : case '9' : digit ++;break; default: other ++; break; } A. if(ch == '-'){ minus++; }else if(ch >= '5' && ch <= '9'){ digit ++; }else { other ++; } B. switch (ch){ default: other ++; break; case '-': minus++; break; case '0' : case '1' : case '2' : case '3' : case '4' : case '5' : case '6' : case '7' : case '8' : case '9' : digit ++;break; } C. if(ch == '-'){ minus++; }else if(ch >= '0' && ch <= '9'){ digit ++; }else { other ++; } D. switch (ch){ case '0' : case '1' : case '2' : case '3' : case '4' : case '-': minus++; break; case '5' : case '6' : case '7' : case '8' : case '9' : digit ++;break; default: other ++; break; }