Help with a specific C program in Ubuntu

[scooter1]

Hi,

I have written a simple C program in Ubuntu 10.10 get editor. The text of the code is shown below.

When I apply the combined gcc compile and link command in the terminal to the file which contains the code below I get the following errors:

Errors
kopy_1.c: In function ‘main’:
kopy_1.c:34: error: ‘uppercase’ undeclared (first use in this function)
kopy_1.c:34: error: (Each undeclared identifier is reported only once
kopy_1.c:34: error: for each function it appears in.)
kopy_1.c:34: error: ‘var’ undeclared (first use in this function)

Can anyone provide some assistance to solve these errors so that I can get the command to work successfully?

Code

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

int main (argc, argv)

int argc;
char *argv[];

{

int i, j ;
int fileArg = 0 ; // Count for files on command line
int infd, outfd ; // File descriptor for input and output file
int num_read, num_write ; // Numbers of characters returned by a file access
char buff [1024] ; // Buffer for use in file access
char* fileName[2] = {} ; // Point to file names


// Parse the command line arguments

for ( i = 1 ; i < argc; i++ )
{
if (argv[i][0] == '-') // Check for a command option

// Simple message display, a real system would process options
printf ("You have selected an option\n");
else fileName[fileArg++] = argv[i];
}


// If uppercase_var is set then convert all buff's characters to uppercase

if(uppercase-var == 1)
{for(i=0; i<sizeof(buff); i++)
if(islower(buff[i]))
buff[i] = toupper(buff[i]);
}

// Open the first file for reading

infd = open (fileName[0], O_RDONLY, 0600 );
if (infd == -1)
{ printf ("Failed to open first file %s\n", fileName[0]);
return 1;
}




// Open/create the second file for writing

outfd = open (fileName[1], O_CREAT | O_WRONLY, 0600 );
if (outfd == -1)
{ printf ("Failed to open second file %s\n", fileName[1]);
close (infd);
return 1;
}


// Now copy the contents of the first file to the second file

while ((num_read = read (infd, buff, sizeof (buff))) > 0)
{
num_write = write (outfd, buff, num_read);

// Check for basic failure
if (num_write != num_read)
{
printf ("Problem - mismatch between write size and read size!\n");
}
}

// Remember to close all open files before exit
close (outfd);
close (infd);

return 0 ;

}

[hazel]

You wrote "uppercase-var" instead of uppercase_var. That subtracts an undeclared variable "var" from an undeclared variable "uppercase". Hence the errors.

ps Now I look again and I don't think you declared uppercase_var either!

[scooter1]

Can you remind me again with suitable code the declaration for the "uppercase_var"?

Can you suggest precise location in the body of the code where said declaration goes.

Thanks

You wrote "uppercase-var" instead of uppercase_var. That subtracts an undeclared variable "var" from an undeclared variable "uppercase". Hence the errors.

ps Now I look again and I don't think you declared uppercase_var either!

[hazel]

You declare it near the top where you've declared your other variables. The simplest way would be to declare it as an integer: int upper_var. You might want to set a default value: int upper_var=0.

A more elegant way would be to define a boolean type with permissible values TRUE and FALSE:

typedef enum boolean {FALSE, TRUE};
boolean upper_var=FALSE;

(I leave it to you to find out why FALSE and TRUE have to be given in that order)

But declaring a variable is only the beginning. You also need to give it a value. Where does your upper_var get its value from? Is it a command line option to the program, something like "-U"? If so, you'll need to go through the argv array (there's a function called getopts that will do that for you) and set upper_var if that option is found; that's why it's useful to have it unset by default.

The key to programming is to think logically and systematically.