在退出函數後，使用realloc將不會存儲數組中的值

Question

將數據庫中的值放入數組中並將值發送到函數本身內的addReader後，值將成功存儲，但返回主輸入的值不見了。

鑑於以下代碼：創建與realloc

reader* readerBuilder(reader *rdr, int *readNum){  //building all the readers 
    FILE *read; 
    int i=1; 
    char *str; 
    read = fopen("Readers.txt","r"); 
    checkFile(read); 
    str = readFromFile(read); 
    while(str != NULL) 
    { 
     rdr[i-1] = *cutToRdr(str); 
     str = readFromFile(read); 
     if(str != NULL){ 
      i++; 
      rdr = (reader*)realloc(rdr,sizeof(reader)*i); 
      checkreader(rdr); 
     } 
    } 
    fclose(read); 
    *readNum = i; 
    return rdr; 
} 

鑑於調用函數中的動態數組：

reader* addReader(reader *rdr, int *readNum){  //adding a reader from the user 
    char string[1000]; 
    rdr = (reader*)realloc(rdr,sizeof(reader)*(*readNum+1));// build new struct array (bigger), with the old values 
    checkreader(rdr);// check if can get memory 
    printf("please enter the I.D. of the student you want to add:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum].id=cutToStr(string);// put id in struct 
    printf("please add the reader's first name:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum].first_name=cutToStr(string);// put first name in struct 
    printf("please add the reader's last name:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum].last_name=cutToStr(string);// put last name in struct 
    printf("please add the reader's address:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum].address=cutToStr(string);// put adress in struct 
    printf("please add the reader's phone:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum].phone=cutToStr(string);// put phone in struct 
    rdr[*readNum].numToTake = 5;// change value of numbers to tke to 5 
    *readNum = *readNum + 1;// rise the number of the readers 
    return rdr;// return the new structs array 
} 

鑑於主調用用於功能：

rdr=addReader(rdr,readNum); 

Defenition讀者結構：

typedef struct reader{ 
    int numToTake; 
    char *first_name, *last_name, *address, *phone, *id; 
}reader; 

我在做什麼錯？ 問候，大衛

編輯！

仍然不起作用。 代碼的新版本：

void addReader(reader **rdr, int *readNum){  //adding a reader from the user 
    char string[1000]; 
    rdr = (reader**)realloc(rdr,sizeof(reader*)*(*readNum+1));// build new struct array (bigger), with the old values 
    checkreader(*rdr);// check if can get memory 
    printf("please enter the I.D. of the student you want to add:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum]->id=cutToStr(string);// put id in struct 
    printf("please add the reader's first name:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum]->first_name=cutToStr(string);// put first name in struct 
    printf("please add the reader's last name:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum]->last_name=cutToStr(string);// put last name in struct 
    printf("please add the reader's address:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum]->address=cutToStr(string);// put adress in struct 
    printf("please add the reader's phone:\n"); 
    scanf("%s",string);// get from operant 
    rdr[*readNum]->phone=cutToStr(string);// put phone in struct 
    rdr[*readNum]->numToTake = 5;// change value of numbers to tke to 5 
    *readNum = *readNum + 1;// rise the number of the readers 
    //return rdr;// return the new structs array 

}

在主要的新電話：

addReader(&rdr,readNum); 

Answer 1

你應該通過**rdr：

reader* addReader(reader **rdr, int *readNum) 
         ^^ 

而且，這增加一個新的間接水平，當你realloc。

用你現在的代碼realloc指針的副本不是實際的指針。