我的地址簿程序存在一個小問題C

Question

我的地址簿中存在一個小問題，如果我嘗試加載聯繫人數據時未輸入並至少保存一個聯繫人信息，程序返回一個「0」並凍結。另外，我覺得我需要在這個程序中添加一個刪除聯繫人功能，如果有人願意幫我解決這個問題，那麼我會非常感激= D。

#include <stdio.h> 
#include <stdlib.h> 
#include <ctype.h> 
#include <string.h> 

#define NAME 40 
#define LNAME 40 
#define ADDRESS 100 
#define PCODE 6 
#define PNUM 10 
#define MAX  10 

void Insert(); 
void Display(); 
void Search(); 
void Save(); 
void Load(); 
void Exit(); 

char temp [10]; 

typedef struct contact //defines the structure for our address book 

{ 
    char name [NAME ]; 
    char Lname [LNAME ]; 
    char address[ADDRESS]; 
    char Pcode [PCODE]; 
    char Pnum [PNUM]; 

} 
contact; 

int counter = 0; 
int placeHolder = 0; 
int loadContact; 

int fileCount; 

int save = 0; 

FILE *PFileOut; 

contact arrayContact [MAX]; 


int main() 
{ 
    int option; 
    char filechar; 

    do 
    { 
    printf("\n***Personal Contact Book V1.0***\n\n"); 
    printf("1.Add new contact\n"); 
    printf("2.Display current contacts\n"); 
    printf("3.Search for a contact\n"); 
    printf("4.Save contacts to file\n"); 
    printf("5.Load contacts to file\n"); 
    printf("6.Exit\n\n"); 
    printf("> "); 

    scanf("%d", &option); 

    switch (option) 
     { 
      case 1: 
       Insert(); 
       break; 

      case 2: 
       Display(); 
       break; 

      case 3: 
       Search(); 
       break; 

      case 4: 
       Save(); 
       break; 

      case 5: 
       Load(); 
       break; 

      case 6: 
       Exit(); 
       break; 

      default: 
       printf("That is not a valid input, please choose between (1-6)"); 

     } 
    } 
    while(option !=6); 
} 

void Insert() 
{ 
     char option; 
     if(placeHolder>=10){ 
       printf("Your contact list is full!"); 
       return; 
     } 
     do{ 
       printf("Contact Number: %d\n", counter+1); 
       printf("First name: "); 
       scanf(" %[^\n]s", arrayContact[counter].name); 
       printf("Last name: "); 
       scanf(" %[^\n]s", arrayContact[counter].Lname); 
       printf("Address: "); 
       scanf(" %[^\n]s", arrayContact[counter].address); 
       printf("Postal Code: "); 
       scanf(" %[^\n]s", arrayContact[counter].Pcode); 
       printf("Phone: "); 
       scanf(" %[^\n]s", arrayContact[counter].Pnum); 

       placeHolder++; 
       counter++; 

       printf("Press y/Y if you wish to add another contact, any key to return to main menu\n"); 
       scanf(" %c",&option); 
       printf("\n"); 

     }while((option =='y'|| option == 'Y')&& placeHolder<MAX); 






} 

void Display() 
{ 
    counter = 0; 
    while(counter<placeHolder){ 
     printf("Contact Number: %d\nFirst Name: %s\nLast Name: %s\nAddress: %s\nPostal Code: %s\nPhone: %s\n\n",counter+1,arrayContact[counter].name, 
     arrayContact[counter].Lname,arrayContact[counter].address,arrayContact[counter].Pcode,arrayContact[counter].Pnum); 
     counter++; 
    } 
    counter = placeHolder; 
} 

void Search() 
{ 
    char search [40]; 
    char compare [40]; 
    int counterLetter; 
    int counterContact; 
    int verify = 0; 

    printf("What is the contact's Last name? "); 
    scanf(" %s", search); 

    for(counterLetter = 0; search[ counterLetter ] != '\0'; counterLetter++) { 
     search[ counterLetter ] = tolower(search[ counterLetter ]); 
    } 

    for(counterContact = 0; counterContact<placeHolder ; counterContact++){ 
     strcpy(compare,arrayContact[counterContact].Lname); 

     for(counterLetter = 0; compare[ counterLetter ] != '\0'; counterLetter++) { 
      compare[ counterLetter ] = tolower(compare[ counterLetter ]); 
     } 

     if(strcmp(search, compare) == 0){ 
      printf("Contact Number: %d\nFirst Name: %s\nLast Name: %s\nAddress: %s\nPostal Code: %s\nPhone: %s\n\n",counterContact+1, 
      arrayContact[counterContact].name,arrayContact[counterContact].Lname,arrayContact[counterContact].address,arrayContact[counterContact].Pcode, 
      arrayContact[counterContact].Pnum); 
      verify = 1; 
     } 
    } 

    if(verify == 0){ 
     printf("No results found"); 
    } 

} 

void Save() 
{ 
    PFileOut = fopen("Contact Book.dat","w"); 
    fprintf(PFileOut,"%d\n",placeHolder); 
    for(counter = 0;counter<placeHolder;counter++){ 
     fprintf(PFileOut,"\n%s\n%s\n%s\n%s\n%s",arrayContact[counter].name,arrayContact[counter].Lname,arrayContact[counter].address,arrayContact[counter].Pcode, 
     arrayContact[counter].Pnum); 
    } 
    fclose(PFileOut); 
    save = 1; 

    printf("\nSuccessfully Saved!!\n"); 
} 

void Load() 
{ 
    char temp[40]; 
    PFileOut = fopen("Contact Book.dat","r"); 
    fscanf(PFileOut, "%d", &fileCount); 
    printf("%d\n", fileCount); 
    while(!feof(PFileOut)){ 
     fscanf(PFileOut,"%s",&arrayContact[placeHolder].name); 
     fscanf(PFileOut,"%s",&arrayContact[placeHolder].Lname); 
     fscanf(PFileOut," %[^\n]s",&arrayContact[placeHolder].address); 
     fscanf(PFileOut,"%s",&arrayContact[placeHolder].Pcode); 
     fscanf(PFileOut, " %[^\n]s",&arrayContact[placeHolder].Pnum); 
     placeHolder++; 
    } 
    fclose(PFileOut); 
} 

void Exit() 
{ char option6; 
    while(save!=1){ 
     printf("It seems you have not saved your progress. Would you like to save? (y/n)"); 
     scanf(" %c", &option6); 
     if(option6 == 'y'|| option6 == 'Y') 
      { 
       Save(); 
      } 
     else 
     { 
      puts ("\nThank you for using Contact Book"); 

      exit(0); 
     } 
    } 
    puts ("\nThank you for using Contact Book"); 
    exit(0); 

} 

Answer 1

你的程序有很多問題。

如果.dat文件不存在，那麼fopen將會失敗，並將文件指針保留爲NULL。 隨後的fscanf也不起作用，這就是爲什麼你的記錄數爲0。 feof與NULL文件指針的行爲是不確定的，所以這可能是你懸掛的地方。所有權利，這個程序應該崩潰。