Problems reading a file in C

Question

I'm trying to read a file in c using fread, but fread didn't show all records, only a few. Note that i write the file using struct and recover the same way. Here's my code:

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

struct data{
    int numero;
};

void read(){
    int i = 1;
    FILE *arquivo = fopen(URL_NEW, "r");
    struct data dataTemp;

    fseek(arquivo,sizeof(struct data),SEEK_SET);

    int leitura;
    while (fread(&dataTemp,1,sizeof(struct data),arquivo))
    {   
        printf("\nNumber = ");
        printf("%d\n",dataTemp.numero);
    }

    fclose(arquivo);        
}

void write(){
    struct data dataTemp;
    FILE *arquivo = fopen(URL_NEW, "w");

    for(int i=1; i < 2000;i++){
        dataTemp.numero = i;

        fwrite(&dataTemp,sizeof(struct data),1,arquivo);
    }

    fclose(arquivo);
}

int main(){
    write();
    read();
}


output:

Number = 2
Number = 3
Number = 4
Number = 5
Number = 6
Number = 7
Number = 8
Number = 9
Number = 10
Number = 11
Number = 12
Number = 13
Number = 14
Number = 15
Number = 16
Number = 17
Number = 18
Number = 19
Number = 20
Number = 21
Number = 22
Number = 23
Number = 24
Number = 25

If i try to to use fseek, they got lost at 10 record. Anyone know know i can fix it or any workaround for my problem?

EDIT: Seems like using rb and wb fixed the problem, thanks! :D

Answer 1

the following proposed code:

1. cleanly compiles
2. performs the desired functionality
3. properly checks for errors
4. does not use well known system function names for local functions however, read() and write() are prototyped in unistd.h so not a direct problem with the code as that header file is not included.

the reason it did not work (well there are a few reasons)

most notably, the compiler will output several warning and error messages. It is a wonder that it ever ran.

When compiling, always enable all the warnings, then fix those warnings.

(for gcc , at a minimum use: -wall -wextra -pedantic -std=gnu11 I also use: `-Wconversion -Wmissing-prototypes -ggdb )

and now the proposed code:

#include <stdio.h>   // perror(), fopen(), FILE, fseek(), fread(), printf(), fclose()
#include <stdlib.h>  // exit(), EXIT_FAILURE
//#include <string.h>

struct data
{
    int numero;
};


// prototypes
void myRead( void );
void myWrite( void );


void myRead()
{

    FILE *arquivo = fopen("/tmp/URL_NEW", "r");
    if( !arquivo )
    {
        perror( "fopen to read URL_NEW failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, fopen successful

    struct data dataTemp;

    // the following 'fseek()' skips over the first record
    if( 0 != fseek(arquivo, sizeof(struct data), SEEK_SET) )
    {
        perror( "fseek failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, fseek successful


    // note: the returned value and the third parameter must match
    while ( 1 == fread(&dataTemp, sizeof(struct data), 1, arquivo))
    {
        printf("\nNumber = ");
        printf("%d\n", dataTemp.numero);
    }

    fclose(arquivo);
} // end function: myRead()


void myWrite()
{
    struct data dataTemp;
    FILE *arquivo = fopen("/tmp/URL_NEW", "w");
    if( !arquivo )
    {
        perror( "fopen to write URL_NEW failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, fopen successful

    for(int i=1; i < 2000;i++)
    {
        dataTemp.numero = i;

        // note: the returned value and the third parameter must match
        if( 1 != fwrite(&dataTemp, sizeof(struct data), 1, arquivo) )
        {
            perror( "fwrite failed" );
            exit( EXIT_FAILURE );
        }

        // implied else, fwrite successful
    }

    fclose(arquivo);
}

int main( void )
{
    myWrite();
    myRead();
}

a sample of the early and late output:

Number = 2 

Number = 3

Number = 4

....

Number = 1996

Number = 1997

Number = 1998

Number = 1999