c - 变量不改变c

Question

嗨，我是一名初级 C 程序员，我正在尝试制作一个过滤器，该过滤器应该根据其他变量来更改变量，但由于某种原因它似乎没有更改变量 g1。我真的很感谢我能得到的任何帮助，因为我现在被困在这里。谢谢

#include <stdio.h>
#include <stdlib.h>
#include <time.h>


int main(void)
{
    int car;
    int g1;
    int g2;
    int sel1;
    unsigned int iseed = (unsigned int)time(NULL);          
    srand (iseed);
    g1 = 0;
    car = rand() % 3 + 1;
    printf("%d\n",car);

    printf("select a door beetween 1 and 3\n ");
    scanf ("%d",&sel1);
    if (sel1 < 0)
    {
        printf("Invalid selection!\n");
        return 0;
    }
    if (sel1 > 3)
    {
        printf("Invalid selection!\n");
        return 0;
    }

    if (sel1 == 1)
    {   
        if(car == 1)
        {
            g1 = 2;
            g2 = 3;
        }   
        if (car == 2);
        {
            g1 = 3;
            g2 = 1;
        }
        if (car == 3);
        {
            g1 = 2;
            g2 = 1;
        } 
    }

    if (sel1 == 2)
    {   
        if(car == 1)
        {
            g1 = 3;
            g2 = 2;
        }   
        if (car == 2);
        {
            g1 = 1;
            g2 = 3;
        }
        if (car == 3);
        {
            g1 = 1;
            g2 = 2;
        } 
    }

        if (sel1 == 3)
    {   
        if(car == 1)
        {
            g1 = 2;
            g2 = 3;
        }   
        if (car == 2);
        {
            g1 = 1;
            g2 = 3;
        }
        if (car == 3);
        {
            g1 = 1;
            g2 = 2;
        } 
    }

    printf("Behind door %d is a goat\n",g1);



    return 0;
}

显然我没有足够的细节，所以忽略这个我只是添加一些随机细节。在初等数学中，变量是表示数字的字母字符，称为变量的值，该值可以是任意的、未完全指定的或未知的。

Answer 1

首先，正如 @BLUEPIXY 建议的那样，您应该删除 ;。

我将更改前两个 sel1 条件以仅设置一个，如下所示:

if (sel1 < 1 || sel1 > 3)
    printf("Invalid selection!\n");

然后我将使用 switch case 和 if 语句:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>


int main(void)
{
    int car;
    int g1;
    int g2;
    int sel1;
    unsigned int iseed = (unsigned int)time(NULL);
    srand(iseed);
    g1 = 0;
    car = rand() % 3 + 1;
    printf("Car= %d\n", car);

    printf("Select a door beetween 1 and 3:\n");
    scanf("%d", &sel1);


    if (sel1 < 1 || sel1 > 3)
        printf("Invalid selection!\n");

    switch (sel1)
    {
    case 1:
        if (car == 1)
        {
            g1 = 2;
            g2 = 3;
        }
        else if (car == 2)
        {
            g1 = 3;
            g2 = 1;
        }
        else if (car == 3)
        {
            g1 = 2;
            g2 = 1;
        }

        break;

    case 2:
        if (car == 1)
        {
            g1 = 3;
            g2 = 2;
        }
        else if (car == 2)
        {
            g1 = 1;
            g2 = 3;
        }
        else if (car == 3)
        {
            g1 = 1;
            g2 = 2;
        }
        break;

    case 3:
        if (car == 1)
        {
            g1 = 2;
            g2 = 3;
        }
        else if (car == 2)
        {
            g1 = 1;
            g2 = 3;
        }
        else if (car == 3)
        {
            g1 = 1;
            g2 = 2;
        }
        break;
    }


    printf("Behind door, %d is a goat\n", g1);


    getchar();
    getchar();  

    return 0;   
}

示例: