Question

我正在编写一个程序，将学生ID存储到5个不同实验室的20台PC中。我几乎得到它，就在程序检测到已经使用过的ID时，它应该打印一个语句并重新启动程序，要求提供学生ID。但是，当我的程序检测到已使用的ID时，它会继续询问实验室然后打印语句，然后继续要求PC预订。

结帐（循环）

for(r=0;r<20;r++)
    {
        if(sId!=l1->pc[r] || sId!=l2->pc[r] || sId!=l3->pc[r] || sId!=l4->pc[r] || sId!=l5->pc[r])
        {
            printf("The Student ID '%i' has not made any booking\n", sId);
            return;
        }
    }

结构代码：

typedef struct
{
    int lId,pc[20],vunit;
}Openlab;

主要

int main()
{
    Openlab lab1;
    Openlab lab2;
    Openlab lab3;
    Openlab lab4;
    Openlab lab5;

    int option;

    lab1.lId = 101;
    lab1.vunit = 20;
    lab1.pc[20];

    lab2.lId = 201;
    lab2.vunit = 20;
    lab2.pc[20];

    lab3.lId = 301;
    lab3.vunit = 20;
    lab3.pc[20];

    lab4.lId = 401;
    lab4.vunit = 20;
    lab4.pc[20];

    lab5.lId = 501;
    lab5.vunit = 20;
    lab5.pc[20];

    printf("***Welcome to OpenLab Booking Service***");
    while(option>3)
    {
        printf("\n\nPlease chose an option:");
        printf("\n[1]Check In");
        printf("\n[2]Check Out");
        printf("\n[0]Quit");
        printf("\n\nOption: ");
        scanf("%i", &option);

        if(option == 1)
        {
            check_in(&lab1,&lab2,&lab3,&lab4,&lab5);
            option = 4;
            printf("\nUnits Vacant Left in Lab 101: %i\n", lab1.vunit);
            printf("Units Vacant Left in Lab 201: %i\n", lab2.vunit);
            printf("Units Vacant Left in Lab 301: %i\n", lab3.vunit);
            printf("Units Vacant Left in Lab 401: %i\n", lab4.vunit);
            printf("Units Vacant Left in Lab 501: %i\n", lab5.vunit);
        }
        else if(option == 2)
        {
            check_out(&lab1,&lab2,&lab3,&lab4,&lab5);
            option = 4;
            printf("\nUnits Vacant Left in Lab 101: %i\n", lab1.vunit);
            printf("Units Vacant Left in Lab 201: %i\n", lab2.vunit);
            printf("Units Vacant Left in Lab 301: %i\n", lab3.vunit);
            printf("Units Vacant Left in Lab 401: %i\n", lab4.vunit);
            printf("Units Vacant Left in Lab 501: %i\n", lab5.vunit);
        }
        else if(option == 0)
        {
            printf("\n\nThanks for using the OpenLab Booking Service! See you again!\n\n");
        }
    }

    return 0;
}

功能：

void check_in(Openlab *l1, Openlab *l2, Openlab *l3, Openlab *l4, Openlab *l5)
{
    int sId,r,lab,comp;

    printf("Please enter your Student ID: ");
    scanf("%i", &sId);

    for(r=0;r<20;r++)
    {
        if(sId!=l1->pc[r] && sId!=l2->pc[r] && sId!=l3->pc[r] && sId!=l4->pc[r] && sId!=l5->pc[r])
        {
            while(lab!=l1->lId && lab!=l2->lId && lab!=l3->lId && lab!=l4->lId && lab!=l5->lId)
            {
                printf("Choose a Open Lab [101,201,301,401,501]: ");
                scanf("%i", &lab);
            }
        }

        else
        {
            printf("The Student ID '%i' has already been used to book a PC!\n", sId);
            break;
        }
    }

    if(l1->vunit!=0 && l2->vunit!=0 && l3->vunit!=0 && l4->vunit!=0 && l5->vunit!=0)
    {
        while(comp>19)
        {
            printf("Choose a PC [0-19]: ");
            scanf("%i", &comp);
        }
    }

    else
    {
        printf("\nNo vacant PC left Open Lab %i!\n\n", lab);
    }

    if(lab==l1->lId)
    {
        //printf("Booking for %i - Lab %i | PC %i ",sId,lab,comp);
        if(l1->vunit!=0)
        {
            l1->vunit--;
            l1->pc[comp] = sId;
        }
    }
    else if(lab==l2->lId)
    {
        //printf("Booking for %i - Lab %i | PC %i ",sId,lab,comp);
        l2->vunit--;
        l2->pc[comp] = sId;
    }
    else if(lab==l3->lId)
    {
        //printf("Booking for %i - Lab %i | PC %i ",sId,lab,comp);
        l3->vunit--;
        l3->pc[comp] = sId;
    }
    else if(lab==l4->lId)
    {
        //printf("Booking for %i - Lab %i | PC %i ",sId,lab,comp);
        l4->vunit--;
        l4->pc[comp] = sId;
    }
    else if(lab==l5->lId)
    {
        //printf("Booking for %i - Lab %i | PC %i ",sId,lab,comp);
        l5->vunit--;
        l5->pc[comp] = sId;
    }
}

退房：

void check_out(Openlab *l1, Openlab *l2, Openlab *l3, Openlab *l4, Openlab *l5)
{
    int sId,r;

    printf("Please Enter your Student ID: ");
    scanf("%i", &sId);

    for(r=0;r<20;r++)
    {
        if(sId==l1->pc[r])
        {
            l1->pc[r] = 0;
            l1->vunit++;
            printf("Removed");
            //return;
        }
        else if(sId==l2->pc[r])
        {
            l2->pc[r] = 0;
            l2->vunit++;
            printf("Removed");
            //return;
        }
        else if(sId==l3->pc[r])
        {
            l3->pc[r] = 0;
            l3->vunit++;
            printf("Removed");
            //return;
        }
        else if(sId==l4->pc[r])
        {
            l4->pc[r] = 0;
            l4->vunit++;
            printf("Removed");
            //return;
        }
        else if(sId==l5->pc[r])
        {
            l5->pc[r] = 0;
            l5->vunit++;
            printf("Removed");
            //return;
        }
    }
}

Answer 1

你的逻辑全都倒退了。您目前获得它的方式是，它循环遍历所有20个插槽并检查所有5个实验室，以查看是否已将学生分配给其中一个。如果它不是，那么你问他们在哪个实验室并继续检查。在询问实验室之前，您应该等到循环结束。

而不是您所拥有的，您应该让它看看是否已分配学生，如果是，请打印出错误消息并从该功能return打印出来，因为那里有没有必要继续。

for(r=0;r<20;r++)
{
    if(sId==l1->pc[r] || sId==l2->pc[r] || sId==l3->pc[r] || sId==l4->pc[r] || sId==l5->pc[r])
    {
        printf("The Student ID '%i' has already been used to book a PC!\n", sId);
        return;
    }
}

如果循环完成，那么您可以询问分配它们的实验室。值得注意的是，您应该在使用之前为lab分配一个值，因为它可以包含任何值，包括有效的实验室ID，这会导致它跳过while循环。或者替代方案，您可以将其设为do...while()循环，因为您始终要至少提出一次问题。

do
{
    printf("Choose a Open Lab [101,201,301,401,501]:\n");
    scanf("%i", &lab);
}
while(lab!=l1->lId && lab!=l2->lId && lab!=l3->lId && lab!=l4->lId && lab!=l5->lId);

如果忽略了其他参数

1 个答案: