Question

After puting the values in data base in an array and sending the values to addReader within the function itself ,the values are stored successfully , however when going back to main the entered values are gone.

Given the following code : creating the dynamic array with 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;
}

Given the calling function :

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
}

Given the calling for function in main:

rdr=addReader(rdr,readNum);

Defenition of the reader struct :

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

What am i doing wrong ?
Regards,David

EDIT!

Still doesn’t work.
The new edition of the code :

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

}

The new calling in main :

addReader(&rdr,readNum);

Answer 1

You should be passing **rdr:

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

Also, this adds a new indirection level when you realloc.

With the code you have now you realloc on a copy of the pointer not the actual pointer.