error in array of structure

Question

I wrote a program using array of structures iam accessing the elements using pointers but iam getting error

#include<stdio.h>
struct book
{
    char name[30]
    int sold;
    int left;
 };
void change(struct book *p);
int main()
{
    char ch;
    int i;
    struct book program[10];
    printf("please enter the information \n ");
    for(i=0;i<10;i++)
    {
            printf(" enter the name of author \n");
            scanf("%s",(program+i).name); // &a[0] is equivalent to a+i 
            printf(" enter the number of book sold \n ");
            scanf("%d"(program+i).sold);
            printf("enter the number of book left \n");
            scanf("%d",(program+i).left);
    }

    printf("the following is the information available \n");
    for(i=0;i<10;i++)
    {
            printf("%s  %d   %d",*(program+i).name,*(program+i).sold,*(program+i).left);
    }
    printf("Do you want to change any data \n press y if yes and any key for no \n");
    ch=getchar();
    if((ch=='y')||(ch=='Y'))
    {
            change(program);
            printf("the following is the information available \n");
            for(i=0;i<10;i++)
            {
                    printf("%s  %d   %d",*(program+i)->name,*(program+i)->sold,*(program+i))->left);
            }

    }
     else
    {
            return 0;
    }
    return 0;
}
void change(struct book *p)
{
    int i;
    for(i=0;i<10;i++)
    {
            printf("enter your data for book %s \n",(p+i)->name);
            printf(" enter the number of book sold \n ");
            scanf("%d",(p+i).old);
            printf("enter the number of book left \n");
            scanf("%d",(p+i).left);
    }
}

the error iam getting is pretty big one

    fncstr.c:18:25: error: request for member ‘name’ in something not a structure or union
   scanf("%s",(program+i).name);
                         ^
fncstr.c:20:13: error: called object is not a function or function pointer
   scanf("%d"(program+i).sold);                                                                                                                
             ^                                                                                                                                 
fncstr.c:22:25: error: request for member ‘left’ in something not a structure or union                                                         
   scanf("%d",(program+i).left);                                                                                                               
                         ^
fncstr.c:28:36: error: request for member ‘name’ in something not a structure or union
   printf("%s  %d   %d",*(program+i).name,*(program+i).sold,*(program+i).left);
                                    ^
fncstr.c:28:54: error: request for member ‘sold’ in something not a structure or union
   printf("%s  %d   %d",*(program+i).name,*(program+i).sold,*(program+i).left);
                                                      ^
fncstr.c:28:72: error: request for member ‘left’ in something not a structure or union
   printf("%s  %d   %d",*(program+i).name,*(program+i).sold,*(program+i).left);
                                                                        ^
fncstr.c:38:37: error: ‘struct book’ has no member named ‘name’
    printf("%s  %d   %d",*(program+i)->name,*(program+i)->sold,*(program+i))->left);
                                     ^
fncstr.c:38:56: error: ‘struct book’ has no member named ‘sold’
    printf("%s  %d   %d",*(program+i)->name,*(program+i)->sold,*(program+i))->left);
                                                        ^
fncstr.c:38:82: error: expected ‘;’ before ‘)’ token
    printf("%s  %d   %d",*(program+i)->name,*(program+i)->sold,*(program+i))-      >left);
                                                                                  ^

Why not use program[i] instead of error prone and obscure pointer arithmetic ? — Eric Fortin
– Eric Fortin, Commented Mar 20, 2015 at 15:05
It is not about speed, under the hood the [] operator will do pointer arithmetic as well but the code will be way more readable. — Eric Fortin
– Eric Fortin, Commented Mar 20, 2015 at 15:30

chmike · Accepted Answer · 2015-03-20 15:08:31Z

3

You have to pass the address of the variables to receive the input.

in main

scanf("%d", &(program+i).sold);

scanf("%d", &(program+i).left);

in change

scanf("%d", &(p+i).old);

scanf("%d", &(p+i).left);

Why not using the notation p[i] and program[i] ? This would make your program more readable.

Another thing is to put a limit for the input of the book name to avoid a buffer overflow:

scanf("%29s",(program+i).name); // &a[0] is equivalent to a+i

edited Mar 20, 2015 at 15:08

answered Mar 20, 2015 at 15:03

chmike

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Comments

R Sahu · Accepted Answer · 2015-03-20 15:08:06Z

2

        scanf("%s", (program+i).name);

Is not right. Type of (program+i) is struct book*. Yes, a pointer. You can't use . to access members from a pointer. You need to use one of the following:

        scanf("%s", program[i].name); 
        scanf("%s", (*(program+i)).name);
        scanf("%s", (program+i)->name);

For the other members, you need to use:

        scanf("%d", &program[i].sold);
        scanf("%d", &program[i].left);

answered Mar 20, 2015 at 15:08

R Sahu

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4 Comments

kapil sharma Over a year ago

this gives me error 'fncstr.c:18:26: error: ‘struct book’ has no member named ‘name’ scanf("%s", program[i].name); '

R Sahu Over a year ago

@kapilsharma, from your error messages, it's clear that the program needs to be fixed at a few more places. Take a look working code at ideone.com/lSbKHg. I changed the for loop limit from 10 to 0 to avoid having to provide input. But the program contains all the compiler error fixes.

R Sahu Over a year ago

@kapilsharma, that error is caused by a missing ; after name in your struct.

kapil sharma Over a year ago

yes sir you are right i checked it just now ,thanks for your time

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