Thread: reading and writing to a file

I gotta be close on this. The new file is not created and I can't figure it out.

Here's what I have.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MaxNameLen 255
#define MaxLineLen 255

int main(int argc, char** argv)
{
    char fileName[MaxNameLen + 1];
    char copyName[MaxNameLen + 1];
    FILE *myfile;
    FILE *newfile;

    printf( "Enter the name of a file to copy from: " );
    fgets( fileName, sizeof( fileName ), stdin );

    if( fileName[strlen( fileName ) - 1] == '\n' )
    {
        fileName[strlen( fileName ) - 1] = '\0';
    }

    myfile = fopen(fileName, "r");
    if (myfile == NULL)
    {
        printf("Cannot open &#37;s\n", fileName);
        return(1);
    }

    fscanf(myfile, "%s", &fileName);

    printf( "Enter the name of a file to copy   to: ");
    fgets( copyName, sizeof( fileName ), stdin );
    
     if( copyName[strlen( copyName ) - 1] == '\n' )
    {
        copyName[strlen( copyName ) - 1] = '\0';
    }

    newfile = fopen(copyName, "w");
    fprintf( newfile, "%s", myfile);

    fclose(myfile);
    fclose(newfile);
    return (0);
}

I wonder if I am actually copying anything.

Any insight?
Thanks

Code:

fscanf(myfile, "%s", &fileName);

What is the purpose of this?

Code:

fgets( copyName, sizeof( fileName ), stdin );

Although no issue because they are the same size, this is a bad practice. The second arg should be sizeof( copyName ).

Also, you should check if newfile is NULL or not.

Code:

fprintf( newfile, "%s", myfile);

This is pure garbage. You're writing a FILE * as if it's a char *. You're going to have issues. You have to actually fgets() or fgetc() the info from the first file and then fprintf(), or fputc() it all into the new file.

i changed thing but I am getting a file that goes on forever.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MaxNameLen 255
#define MaxLineLen 255

int main(int argc, char** argv)
{
    
    char fileName[MaxNameLen + 1];
    char copyName[MaxNameLen + 1];
    FILE *myfile;
    FILE *newfile;
    

    printf( "Enter the name of a file to copy from: " );
    fgets( fileName, sizeof( fileName ), stdin );

    if( fileName[strlen( fileName ) - 1] == '\n' )
    {
        fileName[strlen( fileName ) - 1] = '\0';
    }

    myfile = fopen(fileName, "r");
    if (myfile == NULL)
    {
        printf("Cannot open &#37;s\n", fileName);
        return(1);
    }
    printf( "Enter the name of a file to copy   to: ");
    fgets( copyName, sizeof( copyName ), stdin );

    if( copyName[strlen( copyName ) - 1] == '\n' )
    {
        copyName[strlen( copyName ) - 1] = '\0';
    }

    newfile = fopen(copyName, "w");
    if (newfile == NULL)
    {
        printf("Cannot create %s\n", copyName);
        return(1);
    }

    while (1)
    {
        fgets (fileName , sizeof( fileName ), myfile);
        if (fileName == EOF)
        {
            break;
        }
        else
        {
            fprintf( newfile, "%s", fileName);
        }
    }

    fclose(myfile);
    fclose(newfile);
    return (0);
}

That's an incorrect way to do it. Don't use feof() to control a loop. Use fgets() as your loop condition.

http://faq.cprogramming.com/cgi-bin/...&id=1043284351