我目前正在研究一个模拟堆栈（使用链表）的c库。
堆栈必须能够管理任何数据类型。
它还必须能够将其内容写入文件，然后进行检索。这是我遇到问题的地方。当我将原始堆栈与存储在文件数据中的堆栈进行比较时。
代码如下：
writeRead.c
#include <stdio.h>
#include "stack.h"
#define NODES 3
struct my_data {
int val;
char name[60];
};
int main() {
struct my_stack *s1, *fs1;
struct my_data *data, *data1, *data2;
// Initialize Stack
s1 = my_stack_init(sizeof(struct my_data));
// Initialize data and push to stack
for (int i = 0; i < NODES; i++) {
data = malloc(sizeof(struct my_data)); // We must allocate static memory
data->val = i;
sprintf(data->name, "Value %d", i);
if (my_stack_push(s1, data)) {
puts("Error in my_stack_push()");
exit(1);
}
printf("New node in s1: (%d, %s)\n", data->val, data->name);
}
// Write Stack to file
if (my_stack_write(s1, "/tmp/my_stack.data") == -1) {
puts("Error in my_stack_write (s1)");
exit(1);
}
// Read Stack from file
fs1 = my_stack_read("/tmp/my_stack.data");
if (!fs1) {
puts("Error in my_stack_read (fs1)");
exit(1);
}
// Compare data of stack s1 (memory) and fs1 (file)
while ((data1 = my_stack_pop(s1))) {
printf("FS1 len. %d\n",my_stack_len(fs1));
data2 = my_stack_pop(fs1);
printf("Node of s1: (%d, %s)\t", data1->val, data1->name);
printf("Node of fs1: (%d, %s)\n", data2->val, data2->name);
if (!data2 || data1->val != data2->val || my_strcmp(data1->name, data2->name)) {
printf("Data in s1 and fs1 are not the same.\n (data1->val: %d <> data2->val: %d) o (data1->name: %s <> data2->name: "
"%s)\n",
data1->val, data2->val, data1->name, data2->name);
exit(1);
}
}
return 0;
}
stack.h
#include <fcntl.h> /* Modos de apertura de función open()*/
#include <stdlib.h> /* Funciones malloc(), free(), y valor NULL */
#include <sys/stat.h> /* Permisos función open() */
#include <sys/types.h> /* Definiciones de tipos de datos como size_t*/
#include <unistd.h> /* Funciones read(), write(), close()*/
struct my_stack_node {
void *data;
struct my_stack_node *next;
};
struct my_stack {
int size;
struct my_stack_node *first;
};
int my_strcmp(const char *str1, const char *str2);
struct my_stack *my_stack_init(int size);
int my_stack_push(struct my_stack *stack, void *data);
void *my_stack_pop(struct my_stack *stack);
int my_stack_len(struct my_stack *stack);
struct my_stack *my_stack_read(char *filename);
int my_stack_write(struct my_stack *stack, char *filename);
int my_stack_purge(struct my_stack *stack);
stack.c
#include <stdio.h>
#include "stack.h"
int my_strcmp(const char *str1, const char *str2) {
int restultatCmp = *str1++ - *str2++;
//printf("ResultatCmp : %d \n", restultatCmp);
while(*str1++ && *str2++ && restultatCmp == 0) {
restultatCmp = *str1 - *str2;
}
return restultatCmp;
}
struct my_stack *my_stack_init(int dataSize) {
struct my_stack *stack = malloc(sizeof(struct my_stack));
stack -> first = NULL;
stack -> size = dataSize;
return stack;
}
int my_stack_push(struct my_stack *stack, void *dataIn) {
struct my_stack_node *nodeToPush;
nodeToPush = malloc(sizeof(struct my_stack_node));
if(stack == NULL && sizeof(dataIn)> 0){
printf("Null Stack or data size error.\n");
//la pila debe existir
return -1;
}
else {
nodeToPush -> data = dataIn;
if(stack -> first == NULL) {
nodeToPush -> next = NULL;
stack -> first = nodeToPush;
}
else {
nodeToPush -> next = stack -> first;
stack -> first = nodeToPush;
}
}
return 0;
}
void *my_stack_pop(struct my_stack *stack) {
if(stack -> first == NULL) {
return NULL;
}
struct my_stack_node *nodeToDelete = stack -> first;
void *data = nodeToDelete -> data;
stack -> first = nodeToDelete -> next;
free(nodeToDelete);
return data;
}
int my_stack_len(struct my_stack *stack) {
int numNodes = 0;
struct my_stack_node *currentElement = stack -> first;
while(currentElement != NULL) {
numNodes++;
currentElement = currentElement ->next;
}
return numNodes;
}
void recursiveWrite(struct my_stack_node *nodo, int fileDesc, int sizeData) {
if(nodo ->next != NULL) recursiveWrite(nodo -> next,fileDesc,sizeData);
if(write(fileDesc, nodo -> data, sizeData)== -1){
printf("Error de escritura\n");
return;// error escritura.
}
}
int my_stack_write(struct my_stack *stack, char *filename) {
struct my_stack_node *currentNode = stack -> first;
int fileDesc = open(filename, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
if(fileDesc == -1) {
return -1; // Error open();
}
if(write(fileDesc, &stack -> size, sizeof(stack -> size)) == -1){
return -1; // Error write();
}
int sizeData = stack -> size;
recursiveWrite(currentNode,fileDesc,sizeData);
close(fileDesc);
return my_stack_len(stack);
}
struct my_stack *my_stack_read(char *filename) {
int fileDesc = open(filename, O_RDONLY, S_IRUSR);
if(fileDesc == -1) {
return NULL; // Error open();
}
char *buffer = malloc(sizeof(int));
int readBytes;
if((readBytes = read(fileDesc, buffer, sizeof(int))) == -1){
printf("Error reading data size.\n");
return NULL;
}
int dataSize = 0;
dataSize = (int) *buffer; // parse data Size from buffer.
struct my_stack *stack;
stack = malloc(sizeof(struct my_stack));
stack = my_stack_init(dataSize); // initialize Stack
buffer = realloc(buffer, stack -> size);
if(buffer == NULL){
return NULL;
}
else{
while(read(fileDesc, buffer, stack -> size) > 0) {
if((my_stack_push(stack,buffer))== -1){
printf("Error en my_stack_read: Push error.\n");
return NULL;
}
}
close(fileDesc);
return stack;
}
}
对不起，我试图尽可能简化示例的大型代码。
输出：
New node in s1: (0, Value 0)
New node in s1: (1, Value 1)
New node in s1: (2, Value 2)
FS1 len. 3
Node of s1: (2, Value 2) Node of fs1: (2, Value 2)
FS1 len. 2
Node of s1: (1, Value 1) Node of fs1: (2, Value 2)
Data in s1 and fs1 are not the same.
(data1->val: 1 <> data2->val: 2) o (data1->name: Value 1 <> data2->name: Value 2)
预期输出：
New node in s1: (0, Value 0)
New node in s1: (1, Value 1)
New node in s1: (2, Value 2)
FS1 len. 3
Node of s1: (2, Value 2) Node of fs1: (2, Value 2)
FS1 len. 2
Node of s1: (1, Value 1) Node of fs1: (1, Value 1)
FS1 len. 1
Node of s1: (0, Value 0) Node of fs1: (0, Value 0)
我几乎可以确定文件写入是正确的。经过十六进制编辑器检查，应该正确。
所以我的猜测是我的错误在于文件的读取。
忘了提及该项目的一个局限性，即对I / O的系统调用是强制性的。
任何帮助将不胜感激。
谢谢。
编辑1：
按照@AndrewHenle的建议更改了* my_stack_read（），输出仍然不是预期的。
struct my_stack *my_stack_read(char *filename) {
int fileDesc = open(filename, O_RDONLY, S_IRUSR);
if(fileDesc == -1) {
return NULL; // Error open();
}
char *buffer = malloc(sizeof(int));
ssize_t readBytes;
readBytes = read(fileDesc, buffer, sizeof(int));
if(readBytes == -1) {
return NULL;
}
int dataSize = 0;
dataSize = (int) *buffer; // parse data Size from buffer.
struct my_stack *stack;
stack = malloc(sizeof(struct my_stack));
stack = my_stack_init(dataSize); // initialize Stack
buffer = realloc(buffer, stack -> size);
if(buffer == NULL){
return NULL;
}
else{
while(read(fileDesc, buffer, stack -> size) > 0) {
int push = my_stack_push(stack,buffer);
if(push == -1){
printf("Error en my_stack_read: Push error.\n");
return NULL;
}
}
close(fileDesc);
return stack;
}
答案 0 :(得分：0)
您正在以递归方式写入堆栈。下面的函数首先将堆栈的 last 元素写入文件。它将数据反转。
void recursiveWrite(struct my_stack_node *nodo, int fileDesc, int sizeData) {
if(nodo ->next != NULL) recursiveWrite(nodo -> next,fileDesc,sizeData);
if(write(fileDesc, nodo -> data, sizeData)== -1){
printf("Error de escritura\n");
return;// error escritura.
}
}
要以正确的顺序写入数据，应在write函数之后调用递归函数。我还更改了write函数以将其从if条件中删除。
void recursiveWrite(struct my_stack_node *nodo, int fileDesc, int sizeData) {
int ret;
ret = write(fileDesc, nodo -> data, sizeData);
if(ret == -1){
printf("Error de escritura\n");
return;// error escritura.
}
if(nodo ->next != NULL) recursiveWrite(nodo -> next,fileDesc,sizeData);
}
答案 1 :(得分：0)
解决方案：
我在 * my_stack_read：
中发现了我的错误while(read(fileDesc, buffer, stack -> size) > 0) {
int push = my_stack_push(stack,buffer);
if(push == -1){
printf("Error en my_stack_read: Push error.\n");
return NULL;
}
buffer = malloc(stack -> size);
}
buffer = malloc（stack-> size）; 我已经在for循环之外分配了内存，但没有为后续的读取分配内存。
我认为阅读内容会使用相同的方向覆盖其内容，但这似乎是不可能的。
有人可以解释原因吗？
谢谢大家。