NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/lang/c/16785

Internet Message Format | 1992-11-19 | 1.8 KB

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From: [e-mail] (Jos Horsmeier)
Newsgroups: comp.lang.c
Subject: Re: fwrite & fread
Message-ID: <[e-mail]>
Date: 19 Nov 92 11:04:56 GMT
References: <[e-mail]>
Organization: AND Software BV Rotterdam
Lines: 36

In article <[e-mail]> [e-mail] writes:
|I am using write & fread to read and write to a file. The structure that I
|am writing has 194 bytes. After executing fwrite I check the value, in vari
|able a which is 1 (correct), because I am writing one structure. Then I check
|the values of returned by fclose and ferror and they are also correct i-e 0.
|But when I quit from the program without writing more structures or without
|running any other functions and look for the size of my file it shows that it
|has 414 bytes. Actually, it should have 194 bytes. [ ... ]

No it shouldn't. I assume you're working with 2 byte ints (sizeof(int) == 2),
and no structure element padding. If I add up all the bytes, I get this:

|typedef struct activity{
|    int  id;        /* total =   2 */
|    int  mm;        /* total =   4 */
|    int  dd;        /* total =   6 */
|    int  yy;        /* total =   8 */
|    char day[10];        /* total =  18 */
|    int  hour;        /* total =  20 */
|    int  min;        /* total =  22 */
|    int  end_hour;        /* total =  24 */
|    int  end_min;        /* total =  26 */
|    char location[25];    /* total =  51 */
|       char with_who[20];    /* total =  71 */
|    char phone[11];        /* total =  82 */
|    char subj[30];        /* total = 112 */
|    char note[300];        /* total = 412 */
|       int  flag;        /* total = 414 */
|};

BTW this is not a very useful type definition, you forgot to give
the user defined type its own name.

kind regards,

Jos aka [e-mail]