答案:int main(void) { char operato; double valuel, value2; printf( "Type in an expression: ") ; scanf(" %lf%c%lf", &valuel,&operator, &value2) ; switch(operato) { case ' ' printf( " =%. 2f\n" , valuel value2) ; break; case '-': printf( " = %. 2f\n" , valuel- value2) ; break; case' * ': printf( " = %. 2f\n" , valuel * value2) ; break; case '/' : if(value2 = = 0) printf( " Cannot divide int0 0 " ) ; else printf( " = %. 2f\n" , valuel/value2) ; break; default: printf("Unknown operato\n");break; } return 0; }