Thread: This compiler is driving me nuts

Originally posted by mart_man00
hey, i finally remembered to find my password (its MOD EDIT)

ronin, that does give the output i want but thats not the function i want. yours prints the resaults and thats not too useful, i wanted it to be returned(granted, my idea for this function isnt that useful to begin with). that code does seem familar though

You need to stop programming and take a few [insert time frame here] to study basic logic.

Given a program which prints the exact result to the screen, how would you convert that program so it returns that information instead?

The answer is painfully easy: Copy that data instead to some place and return it.

What is someplace? How about a buffer and then possibly later some allocated memory so I can safely return it?

Problem solved.

Quzah.

Originally posted by mart_man00
i

Code:

/* copy Function - Copies text in string data from start to end and returns the
 * the middle. Start must be >= 1. */
char* copy(char data[], int start, int end) {
    { /* Detect and hopefully correct errors. */
        if(data[0] == '\0') 
            return (NULL);
        if(start == NULL || start < 0 || start == 0)
            start = 1;           
        if(end == NULL || end > strlen(data))
            end = strlen(data);
    }
    
    static char value[255];
    char tmp[255];

I hate to break it to you, but that's horrible looking. Why on earth are you creating an additional scope block just so you can put variables later in the middle of the function instead of logicly where they should be, at the top?

It makes me want to cry. You've already been handed the answer. Just change the output from the screen to a buffer, malloc that much space (plus one), copy the text there, return it.

[edit]
I really hate to keep replying over and over to this thread, but every time I read it, I see something more that just boggles my mind... Take for instance, this little gem:

Originally posted by mart_man00
hey, i finally remembered to find my password (its MOD EDITED)

Does anyone else see anything horribly wrong with this?
[/edit]


Quzah.

quzah, i know you know alot more about this than me, but im not seeing it now. why should you copy a single char at a time when you could do the whole thing? and with my "error checking part", why should i declare anything if theres a error that will stop the function from working? and yeah, it does look really bad, how would you do it?

Originally posted by mart_man00
quzah, i know you know alot more about this than me, but im not seeing it now. why should you copy a single char at a time when you could do the whole thing? and with my "error checking part", why should i declare anything if theres a error that will stop the function from working? and yeah, it does look really bad, how would you do it?

It's already been done how I'd do it, with the exception of returning it. You can use a loop, you don't have to. You can use strncpy if you like.

Basicly, make a buffer, copy the text into it, use a pointer, malloc that amount of memory (the length of the buffer + 1), copy the buffer into it, return.

Or, skip the buffer completely, make sure the start and end fall within the string, malloc that length (+1), copy the code to it, and return it.

Quzah.

Originally posted by mart_man00

ronin, that does give the output i want but thats not the function i want. yours prints the resaults and thats not too useful

true, but as I read it, you only wanted to know how to get "esti"

As for your function. You don't really want to do all that extra work from within your function do you? You might consider checking for errors prior to calling the function as that would eliminate a few redundant lines.

Originally posted by mart_man00
if(data[0] == '\0')

This might not be what you expect from a blank string. Try this

Code:

#include <stdio.h>

int main(void)
{
   char array[80];
   
   printf("Enter a blank string: ");
   fgets(array, 80, stdin);
   
   printf("\nuser entered blank string and array[0] contains %d\n", array[0]);
   
   array[0] = '\0';
   
   printf("setting array[0] = '\\0'\narray[0] now contains %d\n", array[0]); 
   
   return 0;
   
}

quzah knows his stuff... he's bailed me out many times and has corrected many of my bad habits, but I still have more that need attention. :P

i must admit defeat again, i keep getting null when i use this in linux

Code:

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

int main(int argc, char *argv[]) { 
	printf("%s\n", ( copy("testing", 2, 5) ) );

	return 0;
}

int copy(char data[], int start, int end) {
	char value[255];
	char tmp[255];
		strcpy(tmp, data);

	memset( tmp, 8, (start - 1) );
	strncpy( value, tmp, ((end - start) + 2) );
	value[ ((end - start) + 2) ] = '\0';

	return ( atoi(value) );
}

i checked out cplusplus.com/ref/ for how to use atoi, im using it correctly right? it returns the int so i could use it as a return right?

Originally posted by mart_man00
so how could i take a string like "testing" and make it an int? that seems like my real probelm.

What exactly do you mean?

atoi() will take a char array (null terminated), and convert it to an int. So, if you had "1234" as you char array, that would convert to 1234 as an int. However, "testing" is not a number, therefore it will convert to 0 (that is atoi() default value for things it doesn't understand).

So, again, what exactly are you trying to do and how does it relate to this:

Posted by martin_00
what i want may program to do is to find to spots in a inputed array and return what is inbetween. so a call like this

copy("testing", 2, 5); // would give me "esti".