c编程语言中从文件中读取数据到结构中

Question

我想从文本文件中读取数据，并将这些数据保存在变量中，而不仅仅是打印输出。我如何保存这些数据从文本文件中的变量?我试过这样做，但没有成功:

int value1 ; 
object2->value =&value1 ; 
*(object2->value) = value1 ; 

我的txt文件看起来像这样:

INT 
A
5

，我的代码是这样的:

#include <stdio.h>
#include <stdlib.h> // For exit()
struct variable {
char type[10];
char name[10];
int value;
};
int main(){
struct variable *object2=malloc(sizeof(struct variable));
FILE * file= fopen("input.txt", "rb");
if (file != NULL) {
fread(object2, sizeof(struct variable), 1, file);
fclose(file);
}

int value1 ;
object2->value =&value1 ;
*(object2->value) = value1 ;
printf("%dn",value1);
printf("%s/%s/%dn",object2->type,object2->name,object2->value);


}

Answer 1

文件格式:

CHAR
B
6
INT
A
5
FLOAT
C
7

这是我的解决方案:

#include <stdio.h>
#include <stdlib.h> // For exit()
#include <string.h>
#define BUFF_SIZE 1024
#define NAME_TYPE_SIZE 10
#define VALUE_SIZE 20
#define NOT_ENOUGH_MEMORY 1
#define CANT_OPEN_FILE 2
#define FILE_ENDED 3
#define TOO_BIG_STR 4
#define CANT_FORMAT_VALUE 5
#define NOT_FOUND_LINE 6
#define SEARCH_NAME "A"
#pragma warning(disable : 4996) // for vs
struct variable {
char type[NAME_TYPE_SIZE];
char name[NAME_TYPE_SIZE];
int value;
};
int find_var_in_file(char* file_path, char* find_name, struct variable* dest);
int main()
{
struct variable* object2 = malloc(sizeof(struct variable));
if (NULL == object2)
{
printf("not enough memory");
return NOT_ENOUGH_MEMORY;
}
int error = find_var_in_file("input.txt", SEARCH_NAME, object2);
if (CANT_OPEN_FILE == error)
{
return printf("can't open file");
}
if (error == 0)
{
// Printing data to check validity
printf("read: type: %s name: %s value: %d", object2->type, object2->name, object2->value);
int a = object2->value;
// do stuff with a
}
else
{
if (error == NOT_FOUND_LINE)
{
printf("not find the var "" SEARCH_NAME "" in the file");
}
else
{
printf("error reading the file. error code: %d", error);
}
}
free(object2);
return 0;
}
int read_line(char* buffer, int buffer_size, char* dest, int dest_size, FILE* stream)
{
if (!fgets(buffer, buffer_size, stream))
{
return NOT_FOUND_LINE;
}
int read_len = strlen(buffer);
if ('n' == buffer[read_len - 1])
{
if (read_len == 1)
{
return NOT_FOUND_LINE;
}
buffer[read_len - 1] = ''; // remove "n" in the end
}
if (dest_size <= strlen(buffer)) // last chat is null
{
return TOO_BIG_STR;
}
strcpy(dest, buffer);
// clear the read
memset(buffer, '', read_len);
return 0;
}
int find_var_in_file(char* file_path, char* find_name, struct variable* dest)
{
char file_buffer[BUFF_SIZE] = { 0 }; // Buffer to store data
FILE* stream = fopen(file_path, "r");
if (NULL == stream)
{
return CANT_OPEN_FILE;
}
int error = 0;
while (1)
{
// read type
int read_type_result = read_line(file_buffer, BUFF_SIZE, dest->type, NAME_TYPE_SIZE, stream);
if (read_type_result != 0)
{
error = read_type_result;
break;
}
int read_name_result = read_line(file_buffer, BUFF_SIZE, dest->name, NAME_TYPE_SIZE, stream);
if (read_name_result != 0)
{
error = read_name_result;
break;
}
char value_buffer[VALUE_SIZE] = { 0 };
int read_value_result = read_line(file_buffer, BUFF_SIZE, value_buffer, VALUE_SIZE, stream);
if (read_value_result != 0)
{
error = read_value_result;
break;
}
if (0 == strcmp(find_name, dest->name))
{
if (1 != sscanf(value_buffer, "%d", &dest->value))
{
error = CANT_FORMAT_VALUE;
}
break;
}
}
fclose(stream);
return error;
}

你只需要像在main中那样调用函数find_var_in_file。我遍历文件的所有行并搜索var名称。如果有格式化错误或没有在文件中找到var的名称，返回错误代码。

Answer 2

如果您试图读取的文件是文本文件(在您的情况下是这样)，则使用fgets()读取其内容。此外，如果其内容具有一致的格式，则考虑使用sscanf()进行解析。

我不明白为什么你使用指针struct variable来保存数据。您可以简单地使用struct variable对象并使用.

访问其字段。你的代码应该看起来像这样:

#include <stdio.h>
#include <stdlib.h> // For exit()
#include <string.h> // for strlen()
struct variable {
char type[10];
char name[10];
int value;
};
int main()
{
FILE *file = fopen("input.txt", "r");
if (!file) {
fprintf(stderr, "Could not read filen");
return 1;
}
struct variable object2;
char buffer[1024];
while (fgets(buffer, 1024, file)) {
if (sscanf(buffer, "%9s %9s %d", object2.type, object2.name, &object2.value) != 3) {
fprintf(stderr, "Error parsing filen");
fclose(file);
return 1;
}
printf("%s %s %dn", object2.type, object2.name, object2.value);
}
fclose(file);
}

现在，如果您想将文件的所有行存储到variables中以供以后使用，那么首先需要计算文件中的行数(我们称之为n)，然后分配一个大小为n的动态数组。

Answer 3

fscanf(file,"%sn%sn%dn",object2->type,object2->name,&object2->value);