c - 多列的冒泡排序？

Question

我有以下代码仅对一列进行排序，我想按多列排序，例如拳头姓名和姓氏。我想指出，我尝试使用 && 添加另一个 strcmp 语句，但它没有给出正确的结果。这是我的代码：

struct Car tempCar;
 tempCar.CarMake  = (char*)malloc( 200 *sizeof(char));
 tempCar.CarMakeYear  = (char*)malloc( 200 *sizeof(char));
 tempCar.CarModel  = (char*)malloc( 200 *sizeof(char));
 tempCar.Occurances = 0;  

int g, didSwap = 1, limit = newCarsCounter - 1; 

//Sort by make
while (didSwap) {
    didSwap = 0;
    for (g = 0; g < newCarsCounter; g++) {
        if ((strcmp (newCars[g].CarMake, newCars[g+1].CarMake) > 0))
        {
            tempCar.CarMake = newCars[g].CarMake;
            tempCar.CarModel = newCars[g].CarModel;
            tempCar.CarMakeYear = newCars[g].CarMakeYear;
            tempCar.Occurances = newCars[g].Occurances;

            newCars[g].CarMake = newCars[g+1].CarMake;
            newCars[g].CarModel = newCars[g+1].CarModel;
            newCars[g].CarMakeYear = newCars[g+1].CarMakeYear;
            newCars[g].Occurances = newCars[g+1].Occurances;

            newCars[g+1].CarMake = tempCar.CarMake;
            newCars[g+1].CarModel = tempCar.CarModel;
            newCars[g+1].CarMakeYear = tempCar.CarMakeYear;
            newCars[g+1].Occurances = tempCar.Occurances;

            didSwap = 1;
        }
    }
    limit--;
}

Answer 1

假设您要对 进行排序CarMake，那么CarModel只需替换即可：

if ((strcmp (newCars[g].CarMake, newCars[g+1].CarMake) > 0))

和：

if (strcmp(newCars[g].CarMake, newCars[g+1].CarMake) > 0 ||
    (strcmp(newCars[g].CarMake, newCars[g+1].CarMake) == 0 &&
     strcmp(newCars[g].CarModel, newCars[g+1].CarModel) > 0))

因此，只有当CarMake值相等时，我们才会比较CarModel.

在效率方面，您可能只想计算一次比较的结果：

int compareVal = strcmp(newCars[g].CarMake, newCars[g+1].CarMake);
if (compareVal > 0 ||
    (compareVal == 0 &&
     strcmp(newCars[g].CarModel, newCars[g+1].CarModel) > 0))

Answer 2

如果要按品牌排序，则按型号排序：

int CompareCar (struct Car *a, struct Car *b) {
    int cmp = strcmp(a->CarMake, b->CarMake);
    if (cmp != 0) {
        return cmp;
    } else { // equal makes, compare by model
        return strcmp(a->CarModel, b->CarModel);
    }
}

可以缩短为：

int ComapreCar (struct Car *a, struct Car *b) {
    return strcmp(a->CarMake, b->CarMake) || strcmp(a->CarModel, b->CarModel);
}

然后更换

if ((strcmp (newCars[g].CarMake, newCars[g+1].CarMake) > 0))

和

if (CompareCar(&(newCars[g]), &(newCars[g+1]) > 0)