怎么才能把全局变量去掉，改了两天了，实在不会了，我指针不熟悉，希望能给详细一点的回答

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include<string.h>
int x,num;
int cop[5];
char pin[200];
void length(int x)
{
do{ 
    x=0;
    printf("please input your password(8~20):");
    while((pin[x] = getchar())!='\n')
    {
        x=x+1;
    }
    num = x;
    
    if(num>8&&num<=10)
    cop[0]=1;
    else if(num>10&&num<16)
    cop[0]=2;
    else
    cop[0]=3;
    }while(num<=8);
}
void lower(int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if(pin[i]>='a'&&pin[i]<='z')
        {
            cop[1]=1;
            break;
        }
        else
            cop[1]=0;
    }    
    num = num;
}
void upper(int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if(pin[i]>='A'&&pin[i]<='Z')
        {
            cop[2]=1;
            break;
        }
        else
            cop[2]=0;
    }    
        num = num;
}
void digits(int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if(pin[i]>='0'&&pin[i]<='9')
        {
            cop[3]=1;
            break;
        }
        else
            cop[3]=0;
    }    
        num = num;
}
void symbol(int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if((pin[i]>='!'&&pin[i]<='/')||(pin[i]>=':'&&pin[i]<='@')||(pin[i]>='['&&pin[i]<='-')||(pin[i]>='{'&&pin[i]<='~'))
        {
            cop[4]=1;
            break;
        }
        else
            cop[4]=0;
    }
        num = num;    
}
void unique(int num)
{
    int i;
    for(i=0;i<num;i++)
    {
        int j;
        for(j=i+1;j<=num;j++)
        {
            if(pin[i]==pin[j])
            {
                cop[5]=0;
                break;
            }
            else
                cop[5]=1;
        }
        if(cop[5]==0)
            break;
        else{}    
    }
    x = num;    
}
 
int main()
{
     x=0;
     do{
        length(x);
        lower(num);
        upper(num);
        symbol(num);
        digits(num);
        unique(num);
           }while(x<8||x>20);
        switch(cop[0])
        {
        case 1:
            printf("\nthe password is weak\nclick Enter to return to the menu");
            break;
        case 2:
            if(cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==1)
            {
                printf("\nthe password is middle\nclick Enter to return to the menu");
                break;
            }
            else
            {
            printf("\nthe password is weak\nclick Enter to return to the menu");
            break;
            }
        case 3:
            if(cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==1&&cop[5]==1)
            {
                printf("\nthe password is strong\nclick Enter to return to the menu");
                break;
            }
            else 
            if((cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==1&&cop[5]==0)||(cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==0&&cop[5]==1)||(cop[1]==1&&cop[2]==1&&cop[3]==0&&cop[4]==1&&cop[5]==1)||(cop[1]==1&&cop[2]==0&&cop[3]==1&&cop[4]==1&&cop[5]==1)||(cop[1]==0&&cop[2]==1&&cop[3]==1&&cop[4]==1&&cop[5]==1))
            {
                printf("\nthe password is middle\nclick Enter to return to the menu");
                break;    
            }
            else
            {
                printf("\nthe password is weak\nclick Enter to return to the menu");
                break;
            }
        }
        return 0;
}

6、7、8行的全局变量都要删除吗？
那就需要在主函数中定义这些变量，然后作为参数传递给与他们相关的函数。如果需要修改值，则需要使用指针类型
修改如下：

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

int length(int *cop,char *pin,int x)
{
    int num=0;
do{ 
    x=0;
    printf("please input your password(8~20):");
    while((pin[x] = getchar())!='\n')
    {
        x=x+1;
    }
    num = x;
    if(num>8&&num<=10)
    cop[0]=1;
    else if(num>10&&num<16)
    cop[0]=2;
    else
    cop[0]=3;
    }while(num<=8);
    return num;
}
void lower(int *cop,char *pin,int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if(pin[i]>='a'&&pin[i]<='z')
        {
            cop[1]=1;
            break;
        }
        else
            cop[1]=0;
    }    
    num = num;
}
void upper(int *cop,char *pin,int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if(pin[i]>='A'&&pin[i]<='Z')
        {
            cop[2]=1;
            break;
        }
        else
            cop[2]=0;
    }    
}
void digits(int *cop,char *pin,int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if(pin[i]>='0'&&pin[i]<='9')
        {
            cop[3]=1;
            break;
        }
        else
            cop[3]=0;
    }    
}
void symbol(int *cop,char *pin,int num)
{
    int i;
    for(i=0;i<=num;i++)
    {
        if((pin[i]>='!'&&pin[i]<='/')||(pin[i]>=':'&&pin[i]<='@')||(pin[i]>='['&&pin[i]<='-')||(pin[i]>='{'&&pin[i]<='~'))
        {
            cop[4]=1;
            break;
        }
        else
            cop[4]=0;
    }  
}
int unique(int *cop,char *pin,int num)
{
    int i;
    for(i=0;i<num;i++)
    {
        int j;
        for(j=i+1;j<=num;j++)
        {
            if(pin[i]==pin[j])
            {
                cop[5]=0;
                break;
            }
            else
                cop[5]=1;
        }
        if(cop[5]==0)
            break;
        else{}    
    }
    return num;   
}
int main()
{
    int x,num;
    int cop[5];
    char pin[200];
     x=0;
     do{
        num = length(cop,pin,x);
        lower(cop,pin,num);
        upper(cop,pin,num);
        symbol(cop,pin,num);
        digits(cop,pin,num);
        x = unique(cop,pin,num);
           }while(x<8||x>20);
        switch(cop[0])
        {
        case 1:
            printf("\nthe password is weak\nclick Enter to return to the menu");
            break;
        case 2:
            if(cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==1)
            {
                printf("\nthe password is middle\nclick Enter to return to the menu");
                break;
            }
            else
            {
            printf("\nthe password is weak\nclick Enter to return to the menu");
            break;
            }
        case 3:
            if(cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==1&&cop[5]==1)
            {
                printf("\nthe password is strong\nclick Enter to return to the menu");
                break;
            }
            else 
            if((cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==1&&cop[5]==0)||(cop[1]==1&&cop[2]==1&&cop[3]==1&&cop[4]==0&&cop[5]==1)||(cop[1]==1&&cop[2]==1&&cop[3]==0&&cop[4]==1&&cop[5]==1)||(cop[1]==1&&cop[2]==0&&cop[3]==1&&cop[4]==1&&cop[5]==1)||(cop[1]==0&&cop[2]==1&&cop[3]==1&&cop[4]==1&&cop[5]==1))
            {
                printf("\nthe password is middle\nclick Enter to return to the menu");
                break;    
            }
            else
            {
                printf("\nthe password is weak\nclick Enter to return to the menu");
                break;
            }
        }
        return 0;
}