我不明白为什么这段代码不起作用请帮帮我 [英] I cant understand why this code is not working please help me out
问题描述
插入员工姓名后，代码停止工作。
请解决此问题我将保留下面的全部代码。
< b>我尝试了什么：
After inserting employee name the code is stopped working.
Please solve this problem i will keep the whole code below.
What I have tried:
#include <stdio.h>
#include <stdlib.h>
#include<malloc.h>
typedef struct emp
{
int id;
char nm;
struct emp *prev;
struct emp *next;
}list;
list *start;
list *end;
///////////////////////////////////// Functios /////////////////////////////////////
void initlist (void);
struct emp *create_emp(void);
void append_emp( struct emp *element);
int delete_emp(int d);
void edit_emp(int old , int current);
list *display ();
struct emp *search_emp(int s);
//////////////////////////////////////////////////////////////////////
///////////////////////////////////// MAIN ////////////////////////////
//////////////////////////////////////////////////////////////////////
int main()
{
int cases;
char nm1;int id1;list *c1; list *i1;
int c2,del;
int old3,new3;
int i5;list *c5;
initlist();
printf("\nLinked List for Employees\n");
printf("---------------------------------------------\n");
printf("Press 1 to INSERT an Employee into the list \n");
printf("Press 2 to DELETE an Employee from the list \n");
printf("Press 3 to EDIT Employee \n");
printf("Press 4 to DISPLAY the list \n");
printf("Press 5 to SEARCH the list \n");
printf("Press 6 to EXIT the program\n");
printf("---------------------------------------------\n");
while (1)
{
scanf("%d",&cases);
if (cases ==6)
{
break;
}
switch(cases)
{
case 1: //why when i run this code it's stop working
c1=create_emp();
append_emp(c1);
printf("Enter the new name : ");
scanf("%c\n",& nm1);
printf("Enter the new id : ");
scanf("%d\n",& id1);
i1 ->id =id1;
c1->nm=nm1;
break;
case 2: //why when i run this code it's stop working
printf("Enter the Employee id you want to delete\n");
scanf("%d\n",c2);
del=delete_emp(c2);
if (del == 0)
{
printf("Not found");
}
else
{
printf("Removed form list");
}
break;
case 3: //why when i run this code it's stop working
printf("Enter the Employee id you want to Edit \n");
scanf("%d",old3);
printf("Enter the new Employee id");
scanf("%d",new3);
edit_emp(old3,new3);
break;
case 4:
display();
break;
case 5:
printf("Enter the id you'r searching for :");
scanf("%d",i5);
c5=search_emp(i5);
if(c5==NULL)
printf("not found\n");
else
printf("found\n");
break;
}
}
}
///////////////////////////////////// Creat list ///////////////////////////
void initlist (void)
{
start=end=NULL;
}
///////////////////////////////////// Create emp /////////////////////////////////////
struct emp *create_emp(void)
{
return ((struct emp*)malloc(sizeof(struct emp)));
}
///////////////////////////////////// Insert emp /////////////////////////////////////
void append_emp( struct emp *element )
{
if ((start==NULL)&&(end==NULL))
{
start=element;
end=element;
element->next=NULL;
element->prev=NULL;
}
else
{
end->next=element;
element->prev=end;
end=element;
element->next=NULL;
}
}
///////////////////////////////////// Delete emp /////////////////////////////////////
int delete_emp(int d)
{
struct emp *temp;
temp=search_emp (d);
if(temp==NULL)
return 0;
if(start==end)
{
start=NULL;
end=NULL;
free(temp);
return 1;
}
else if(temp==start)
{
start=start->next;
start->prev=NULL;
free(temp);
return 1;
}
else if (temp==end)
{
end=temp->prev;
end->next=NULL;
free(temp);
return 1;
}
else
{
temp->prev->next=temp->next;
temp->next->prev=temp->prev;
free(temp);
return 1;
}
}
///////////////////////////////////// Edit emp /////////////////////////////////////
void edit_emp(int old , int current)
{
list * temp;
temp = search_emp(old);
if (temp==NULL)
{
printf("NOT EXIST\n");
}
else
{
temp->id =current;
}
}
///////////////////////////////////// Display list /////////////////////////////////////
list *display ()
{
int d=1;
list*temp;
temp=start;
while (temp!=NULL)
{
printf("The Employee %d ID is : %d\n",d,temp->id);
temp=temp->next;
d++;
}
}
///////////////////////////////////// Search dy ID /////////////////////////////////////
struct emp *search_emp(int s)
{
struct emp *temp;
temp=start;
while((temp!=NULL)&&(temp->id!=s))
{
temp=temp->next;
}
return temp;
}
推荐答案
您的清单* i1未创建：
Your list * i1 is not created:
switch(cases)
{
case 1: //why when i run this code it's stop working
c1=create_emp();
append_emp(c1);
printf("Enter the new name : ");
scanf("%c\n",& nm1);
printf("Enter the new id : ");
scanf("%d\n",& id1);
// because you are missing this part:
i1 = create_emp();
i1->id =id1;
c1->nm=nm1;
break;
您知道我是怎么找到的吗？我调试了你的代码！
也许你下次自己应该这样做？ ：）
And do you know how have I found it? I have debugged your code!
Maybe you should do it next time by your self? :)
编译并不意味着你的代码是正确的！ ：笑：
将开发过程想象成编写电子邮件：成功编译意味着您使用正确的语言编写电子邮件 - 例如英语而不是德语 - 而不是电子邮件包含您的邮件想发送。
所以现在你进入第二阶段的发展（实际上它是第四或第五阶段，但你将在之后的阶段进入）：测试和调试。
首先查看它的作用，以及它与你想要的有何不同。这很重要，因为它可以为您提供有关其原因的信息。例如，如果程序旨在让用户输入一个数字并将其翻倍并打印答案，那么如果输入/输出是这样的：
Compiling does not mean your code is right! :laugh:
Think of the development process as writing an email: compiling successfully means that you wrote the email in the right language - English, rather than German for example - not that the email contained the message you wanted to send.
So now you enter the second stage of development (in reality it's the fourth or fifth, but you'll come to the earlier stages later): Testing and Debugging.
Start by looking at what it does do, and how that differs from what you wanted. This is important, because it give you information as to why it's doing it. For example, if a program is intended to let the user enter a number and it doubles it and prints the answer, then if the input / output was like this:
Input Expected output Actual output
1 2 1
2 4 4
3 6 9
4 8 16然后很明显问题出在将它加倍的位 - 它不会将自身加到自身上，或者将它乘以2，它会将它自身相乘并返回输入的平方。
所以，你可以查看代码和很明显，它在某处：
Then it's fairly obvious that the problem is with the bit which doubles it - it's not adding itself to itself, or multiplying it by 2, it's multiplying it by itself and returning the square of the input.
So with that, you can look at the code and it's obvious that it's somewhere here:
int Double(int value)
{
return value * value;
}
一旦你知道可能出现的问题，就开始使用调试器找出原因。我不能告诉你如何使用你的调试器 - 我不知道你可以使用哪些 - 但是一个快速的谷歌，你的IDE名称和调试器这个词几乎肯定会给你一个教程。在方法的第一行放置一个断点，然后运行你的应用程序。当它到达断点时，调试器将停止，并将控制权移交给您。您现在可以逐行运行代码（称为单步执行）并根据需要查看（甚至更改）变量内容（哎呀，您甚至可以更改代码并在需要时再试一次）。 />
在执行代码之前，请考虑代码中的每一行应该做什么，并将其与使用Step over按钮依次执行每一行时实际执行的操作进行比较。它符合您的期望吗？如果是这样，请转到下一行。
如果没有，为什么不呢？它有什么不同？
希望这可以帮助你找到代码的哪个部分有问题，以及问题是什么。
这是一项技能，它是一个值得开发的，因为它可以帮助你在现实世界和发展中。和所有技能一样，它只能通过使用来改进！
Once you have an idea what might be going wrong, start using the debugger to find out why. I can't tell you how to use your debugger - I have no idea which ones you have available to you - but a quick Google with the name of your IDE and the word "debugger" will almost certainly get you a tutorial. Put a breakpoint on the first line of the method, and run your app. When it reaches the breakpoint, the debugger will stop, and hand control over to you. You can now run your code line-by-line (called "single stepping") and look at (or even change) variable contents as necessary (heck, you can even change the code and try again if you need to).
Think about what each line in the code should do before you execute it, and compare that to what it actually did when you use the "Step over" button to execute each line in turn. Did it do what you expect? If so, move on to the next line.
If not, why not? How does it differ?
Hopefully, that should help you locate which part of that code has a problem, and what the problem is.
This is a skill, and it's one which is well worth developing as it helps you in the real world as well as in development. And like all skills, it only improves by use!
对于代码中常见的问题问题，调试器就是如此。从这个调试器教程中学习如何使用它。
我猜你会发现你的代码有问题，比如副本或者某些无效的内存指针是免费的。
For that common problem of issues in the code the debugger is made. Learn from this debugger tutorial how to use it.
I guess you will find a problem with your code like a copy or free on some invalid memory pointer.
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