C 使用通用链表/变量时未初始化
因此，我试图为赋值编写一个通用程序，该程序一直告诉我，list变量正在使用中，但没有初始化。 我已经尽了我所能，但仍然没有起到任何作用，所以如果有人能告诉我我做错了什么，我将不胜感激 代码有点长，所以请耐心听我说 标题内容：C 使用通用链表/变量时未初始化,c,C,因此，我试图为赋值编写一个通用程序，该程序一直告诉我，list变量正在使用中，但没有初始化。 我已经尽了我所能，但仍然没有起到任何作用，所以如果有人能告诉我我做错了什么，我将不胜感激 代码有点长，所以请耐心听我说 标题内容： #ifndef _HEADER_H #define _HEADER_H #include <stdio.h> #include <stdlib.h> #include <string.h> #include <conio.h>
#ifndef _HEADER_H
#define _HEADER_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
typedef enum { FALSE, TRUE } BOOL;
/* defining specific function names*/
typedef int(*compare_func)(void*, void*);
typedef void(*print_func)(void*);
typedef void(*free_func)(void*);
/* defining struct names and pointers*/
typedef struct set Set;
typedef struct set* PSet;
typedef struct list List;
typedef struct list* PList;
/* creating and initialzing a set*/
PList createSet(PList List, compare_func cmp_fnc, print_func prnt_fnc, free_func free_fnc);
/* finding the biggest value in the set*/
void* findMax(PList List);
/* finding the smallest value in the set*/
void* findMin(PList List);
/* finding an element in the set*/
BOOL findInSet(PList List, void* val);
/* function for finding the size of the list*/
int setSize(PList list);
/* inserting a new element.*/
BOOL addToSet(PList List, void *data);
/* deleting an element, pointered by todel*/
BOOL deleteFromSet(PList list, void *todel);
/* print the elements in the set */
void printAll(PList list);
/* deleting the entire set */
void deleteSet(PList list);
#endif
#include "Header.h"
void prnt_string(void* str) // specific function for printing strings
{
puts(*(char*)str);
printf(" ");
}
void free_string(void* str) // specific function for freeing memory
{
free(str);
}
int cmp_str(void* s1, void* s2) // specific function for comparing two strings
{
if (strcmp(*(char*)s1, *(char*)s2) == 0)
return 0;
else if (strcmp(*(char*)s1, *(char*)s2 == 1))
return 1;
else return -1;
}
void prnt_int(void* a) // Specific function for printing integers
{
printf("%d ", a);
}
void free_int(void* a) // Specific funtion for freeing integers
{
free(a);
}
int int_comp(void* a, void* b) // Specific function for printing integers
{
if (*(int*)a == *(int*)b)
return 0;
else if (*(int*)a > *(int*)b)
return 1;
else return -1;
}
int main()
{
char ch, tempstr[31], *str;
int n, option, *num, item;
void *temp;
BOOL status;
PList list;
printf("Choose the type you want to work with:\n");
printf("1. Integers\n");
printf("2. Strings\n");
printf("Enter input: ");
scanf("%d", &n);
switch (n)
{
case 1:
list = createSet(list, int_comp, prnt_int, free_int);
do
{
printf("Choose the desired action: ('-1' to exit)\n");
printf("1. Create a Set\n");
printf("2. Add To Set\n");
printf("3. Delete From Set\n");
printf("4. Find an Item in The Set\n");
printf("5. Find The Biggest Value In The Set\n");
printf("6. Find The Smallest Value In The Set\n");
printf("7. Delete The Set\n");
printf("Enter input: ");
scanf("%d", &option);
switch (option)
{
case 1:
list = createSet(list, int_comp, prnt_int, free_int);
printf("The Set Has Been Initialized.\n");
break;
case 2:
num = (int*)malloc(sizeof(int));
if (num == NULL)
{
printf("Memory allocation failed!");
deleteSet(list);
return 1;
}
else
{
printf("Enter a number: ");
scanf("%d", &num);
status = addToSet(list, num);
if (status == TRUE)
{
printf("Number successfully added to set.\n");
printAll(list);
}
else
{
printf("Operation failed!\nThe number already exists in the set or memory allocation failed.\n");
deleteSet(list);
return 1;
}
}
break;
case 3:
printf("Enter number: ");
scanf("%d", &item);
status = deleteFromSet(list, &item);
if (status == TRUE)
{
printf("Number successfully deleted.\n");
printAll(list);
}
else
{
printf("Operation failed!\nThe number does not exist in the set.");
printAll(list);
}
break;
case 4:
printf("Enter number: ");
scanf("%d", &item);
if (findInSet(list, &item) == TRUE)
printf("Item exists in the set.\n");
else if (findInSet(list, &item) == FALSE) printf("Item does not exist in the set.\n");
/*else if (findInSet(list, &item) == NULL) printf("The set is empty.\n");*/
break;
case 5:
printf("The size of the set is %d", setSize(list));
break;
case 6:
temp = findMax(list);
if (temp == NULL) printf("The set is empty.\n");
else printf("The biggest value in the set is %d", (int*)temp);
break;
case 7:
temp = findMin(list);
if (temp == NULL) printf("The set is empty.\n");
else printf("The smallest value in the set is %d", (int*)temp);
break;
case 8:
deleteSet(list);
break;
}
} while (option != -1);
deleteSet(list);
break;
case 2:
list = createSet(list, cmp_str, prnt_string, free_string);
do
{
printf("Choose the desired action: ('-1' to exit)\n");
printf("1. Create a Set\n");
printf("2. Add To Set\n");
printf("3. Delete From Set\n");
printf("4. Find an Item in The Set\n");
printf("5. Find The Biggest Value In The Set\n");
printf("6. Find The Smallest Value In The Set\n");
printf("7. Delete The Set\n");
printf("Enter input: ");
scanf("%d", &option);
switch (option)
{
case 1:
list = createSet(list, cmp_str, prnt_string, free_string);
printf("The Set Has Been Initialized.\n");
break;
case 2:
printf("Enter a string(max of 30 characters): ");
gets(tempstr);
str = (char*)malloc(strlen(tempstr) + 1 * sizeof(char));
if (str == NULL)
{
printf("Memory allocation failed!\n");
deleteSet(list);
return 1;
}
strcpy(str, tempstr);
status = addToSet(list, str);
if (status == TRUE)
{
printf("String successfully added to set.\n");
printAll(list);
}
else
{
printf("Operation failed!\nThe string already exists in the set or memory allocation failed.\n");
deleteSet(list);
return 1;
}
break;
case 3:
printf("Enter string(max of 30 characters): ");
gets(tempstr);
status = deleteFromSet(list, &tempstr);
if (status == TRUE)
{
printf("String successfully deleted.\n");
printAll(list);
}
else
{
printf("Operation failed!\nThe string does not exist in the set.");
printAll(list);
}
break;
case 4:
printf("Enter string: ");
gets(tempstr);
if (findInSet(list, &tempstr) == TRUE)
printf("Item exists in the set.\n");
else if (findInSet(list, &tempstr) == FALSE) printf("Item does not exist in the set.\n");
/*else if (findInSet(list, &tempstr) == NULL) printf("The set is empty.\n");*/
break;
case 5:
printf("The size of the set is %d", setSize(list));
break;
case 6:
temp = findMax(list);
if (temp == NULL) printf("The set is empty.\n");
else
{
printf("The biggest value in the set is ");
puts((char*)temp);
}
break;
case 7:
temp = findMin(list);
if (temp == NULL) printf("The set is empty.\n");
else
{
printf("The smallest value in the set is ");
puts((char*)temp);
}
break;
case 8:
deleteSet(list);
break;
}
} while (option != -1);
deleteSet(list);
break;
default:
printf("Wrong input!\n");
break;
}
getch();
return 0;
}
问题可能是什么？每个变量在读取之前都应该初始化，否则从中读取的任何内容都是垃圾。在C语言中，变量在默认情况下不会像在其他一些语言中那样初始化 在
createSet（）LISTLISTListListPList List&listPListcreateSet（）PListPList列表，以便：
List fooList;
PList pFooList = &fooList;
createSet(pFooList, ...):
然后在createSet（）
中，不要使用malloc
分配新对象
但是，您也可以在createList（）
中创建对象，但不要传递任何PList
第一个选项的优点是，如果要动态分配对象，可以使用：
PList pFooList = malloc(sizeof(List));
createSet(pFooList, ...);
但是您不必这样做，因为您仍然可以在堆栈上分配对象
注
正如@MichaelBeer所评论的，声明的变量static
实际上会自动初始化，但这并不能解决询问者的问题，因为如果list
是用static PList list
声明的，然后list
将指向NULL
，而不仅仅是垃圾。每个变量在读取之前都应该初始化，否则从中读取的任何内容都是垃圾。在C语言中，变量在默认情况下不会像在其他一些语言中那样初始化
在createSet（）
函数中，您取消引用变量LIST
，但main中的LIST
只是声明为指针，而没有初始化它以实际指向某个对象
您应该在main中使用List
来声明List
，而不是PList List
。然后将&list
传递给接受PList
参数的函数
另外，当前的createSet（）
函数正在混合两种初始化对象的方法
您可以将PList
传递给它，然后初始化PList
指向的列表，以便：
List fooList;
PList pFooList = &fooList;
createSet(pFooList, ...):
然后在createSet（）
中，不要使用malloc
分配新对象
但是，您也可以在createList（）
中创建对象，但不要传递任何PList
第一个选项的优点是，如果要动态分配对象，可以使用：
PList pFooList = malloc(sizeof(List));
createSet(pFooList, ...);
但是您不必这样做，因为您仍然可以在堆栈上分配对象
注
正如@MichaelBeer所评论的，声明的变量static
实际上会自动初始化，但这并不能解决询问者的问题，因为如果list
是用static PList list
声明的，那么list
将指向NULL
，而不仅仅是垃圾。@MichaelBeer，你确实是对的，但我想确保不提及他们，不提及解决提问者问题的方法：）@MichaelBeer，你确实是对的，但我想确保不提及他们，不提及解决提问者问题的方法：）