如何从C

Question

我知道如何硬编程序来接收文件但是当我尝试使用scanf类似的策略时，没有任何反应。我的意思是我有一个错误检查，看看它是否存在以及它是否具有正确的格式，但每次我输入文件名时都会在scanf下面打印printf语句。这是为什么？我还发现我打开文件但是while语句是无限的。哪个没有意义。我尝试了下面显示的另一个解决方案但结果相同。

void parseFile(struct student_record_node** head)
{
        FILE*input;
        const int argCount = 4;
        char filename[100]="";
        const char rowformat[] = "%20s %20s %d %d";

        struct student_record record;

        struct student_record_node* node = NULL;
        printf("\n Please Enter the FULL Path of the .txt file you like to load. \n");
        scanf("%s",filename);
        input = fopen(filename, "r");
          printf("I am here");
        if(input == NULL)
        {
            printf("Error: Unable to open file.\n");

            exit(EXIT_FAILURE);
        }

        while(!feof(input))
        {
            /* creating blank node to fill repeatedly until end of document*/
            memset(&record, 0, sizeof(struct student_record));
                if(fscanf(input, rowformat, record.first_name_,record.last_name_,&record.student_id_,&record.student_age_) != argCount)
                {

                    continue;
                }
            /* set node into the doubly linked list */
            node = student_record_allocate();

            /* copies values from the blank node reading from document into node in my linked list */
            strcpy(node->record_->first_name_, record.first_name_);

            strcpy(node->record_->last_name_, record.last_name_);

            node->record_->student_id_ = record.student_id_;

            node->record_->student_age_ = record.student_age_;

            /* check if node right after absolute head is empty if so fills it */
            if(*head == NULL)
            {
              *head = node;

            }
            else
            {
            printf(" stuck in loop\n");
              /* if current isn't null start linking the node in a list */
              appendNode(head,node);
            }       


        }

fclose(input);
printf(" end of parsefile");
}

当我进入parsefile（）函数并输入正确格式的NEW.txt并且与程序本身位于同一文件夹内。我知道当我输入一个不存在的.txt文件或者它是空的时，我的检查工作正常。它会像它应该被捕获一样。

预期的行为是程序应该从new.txt加载此列表并将其加载到双向链表中。然后返回到提供用户选项的菜单。然后可以操纵所列出的双重链接，例如添加学生操纵数据，删除，保存和打印当前名单。我从这个程序使用gdb时遇到了麻烦，因为我从parsefile收到了new.txt。

New.txt内容示例。 （它只是名字，姓氏，身份证，年龄）

Belinda Homes 345 50

Scott Crown 456 18

解决方案失败：使用fgetc而不是feof

      int c = fgetc(input);
    while(c != EOF)
    {
      printf("\n in loop \n");
        /* creating blank node to fill repeatedly until end of document*/
        memset(&record, 0, sizeof(struct student_record));
            if(fscanf(input, rowformat, record.first_name_,record.last_name_,&record.student_id_,&record.student_age_) != argCount)
            {

                continue;
            }
        /* set node into the doubly linked list */
        node = student_record_allocate();

        /* copies values from the blank node reading from document into node in my linked list */
        strcpy(node->record_->first_name_, record.first_name_);

        strcpy(node->record_->last_name_, record.last_name_);

        node->record_->student_id_ = record.student_id_;

        node->record_->student_age_ = record.student_age_;

        /* check if node right after absolute head is empty if so fills it */
        if(*head == NULL)
        {
          *head = node;

        }
        else
        {
        printf(" stuck in loop\n");
          /* if current isn't null start linking the node in a list */
          appendNode(head,node);

        }       

    c = fgetc(input);
    }

Answer 1

这是从文件读取和打印输出的最简单方法。我假设你想打印文件或用它做一些事情。

int c;
FILE *file;
file = fopen("test.txt", "r");
if (file) {
    while ((c = getc(file)) != EOF){
        putchar(c);
    }
    fclose(file);
}