我无法显示二进制内容

Question

我正在尝试编写一个简单的电话簿程序。我完成了第一个功能，根据我观察它的工作原理没有错误。但是，在第二个功能（即“display（）”）中，输入人知识后无法向用户显示。我正在使用二进制模式。第二个功能中的问题是我无法理解的。如果你检查并帮助我会很满意。提前致谢。

#include <stdio.h> 
#include <stdlib.h>  // "stdlib" library contains of exit() function 
#include <malloc.h>  // "malloc" library contains of malloc() function 
#include <Windows.h> // "Windows" library contains of Sleep() function which waits the system as you want 
#include <io.h>  // "io" library contains of filelength() function 

struct personKnowledge 
{ 
    char name[32]; 
    char surname[32]; 
    char number[32]; 
}; 

FILE *ptrFILE,*ptrFILE1; 
long int recordLength,totalRecordLength,location; 
static int counter = 0; 
int number,totalRecordNumber; 

void newRecord(); 
void display(); 
void deletE(); 
void add(); 
void update(); 

int main() 
{ 
    int choice; 
    do 
    { 
     printf("\n\t\t --- Phone Book Program ---"); 
     printf("\n\n\t\t 1) New record"); // The options are being presented to user 
     printf("\n\n\t\t 2) Display person knowledge"); 
     printf("\n\n\t\t 3) Delete someone"); 
     printf("\n\n\t\t 5) Update person knowledge"); 
     printf("\n\n\t\t 6) Exit"); 
     printf("\n\n\nEnter your choice: "); 
     scanf("%d", &choice); 
     switch (choice) 
     { 
     case 1: 
     { 
      newRecord(); 
      break; 
     } 
     case 2: 
     { 
      display(); 
      break; 
     } 
     case 3: 
     { 
      break; 
     } 
     case 4: 
     { 
      break; 
     } 
     case 5: 
     { 
      break; 
     } 
     case 6: 
     { 
      printf("\nWorking has been completed.\n"); 
      return 0; 
     } 
     default: 
     { 
      printf("\nWrong entry! The program has been terminated.\n"); 
      break; 
     } 
     } 
    } while (choice >= 1 && choice <= 6); 
    return 0; 
} 

void newRecord() 
{ 
    if ((ptrFILE = fopen("Phone Book.dat", "wb")) == NULL) 
    { 
     printf("The file couldn't open\n"); 
     exit(0); 
    } 
    system("cls"); // Screen is being cleaned 
    struct personKnowledge *p; // p means person 
    p = (struct personKnowledge *)malloc(sizeof(struct personKnowledge)); // Memory is being allocated 
    fflush(stdin); 
    recordLength = sizeof(p); // size of p 
    printf("|| For the %d. person ||\n", counter+1); 
    printf("\n\Express person name: "); // User is entering the person's knowledge and they are being saved in file 
    gets(p->name); 
    printf("Express %s's surname: ", p->name); 
    gets(p->surname); 
    printf("Express %s's number: ", p->name); 
    gets(p->number); 
    fwrite(&(*p), recordLength, 1, ptrFILE); 
    printf("\nPlease wait, information is saving to file..\n"); 
    Sleep(750); 
    printf("*-* Saving operation has been completed succesfully. *-*\n"); 
    free(p); 
    counter++; 
    fclose(ptrFILE); 
} 

void display() 
{ 
    if ((ptrFILE = fopen("Phone Book.dat", "rb")) == NULL) 
    { 
     printf("The file couldn't open\n"); 
     exit(0); 
    } 
    system("cls"); // Screen is being cleaned 
    struct personKnowledge *s; // s means searching 
    s = (struct personKnowledge *)malloc(sizeof(struct personKnowledge)); 
    fflush(stdin); 
    recordLength = sizeof(s); 
    totalRecordLength = filelength(fileno(ptrFILE)); 
    totalRecordNumber = totalRecordLength/recordLength; 
    printf("\n\nExpress person record number which you search: "); 
    scanf("%d", &number); 
    location = (number - 1)*recordLength; 
    fseek(ptrFILE, location, SEEK_SET); 
    fread(&(*s), recordLength, 1, ptrFILE); 
    printf("\n*-* Person knowledge which you search *-*\n"); 
    Sleep(750); 
    printf("Name: %s\n", s->name); 
    printf("Surname: %s\n", s->surname); 
    printf("Number: %s\n", s->number); 
    free(s); 
    fclose(ptrFILE); 
} 

Answer 1

是错误的，这是指针通常4是在64位SYSTE在32位系统和8上的大小。

你需要

recordLength = sizeof(*p); 

或

sizeof(struct personKnowledge); 

，让你的结构的大小通过p指出。