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Apr 22nd, 2005

total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast"

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When trying to compile a C program including the code below, I keep getting this error and I don't know what to do to fix it. Please explain if you can!

Complete code may be downloaded from my website at www.atrixnet.com/cquestion.zip (It's only 2 Kb)

I suppose I'll attach it to this post too, since that appears to be an available feature on this board

COMPILATION ATTEMPT:
tommy@city-it ~/cdevel
$ gcc -Wall -ansi -pedantic -mno-cygwin -I . -o myfirstlib myfirstlib.c

ERROR:
myfirstlib.c: In function `main':
myfirstlib.c:14: warning: passing arg 2 of `strcpy' makes pointer from integer without a cast
myfirstlib.c:20: warning: passing arg 2 of `strcpy' makes pointer from integer without a cast

CODE SUMMARY (main program):

C++ Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
#include <myfuncs.h>
 
int anumber;
char astring[255];
 
int
main ()
{
  printf ("This is the first time I've tried to '#include' my library!\n\n");
 
  anumber = getnum("Enter some kind of integer: ");
  strcpy(astring, getstring("Enter your name: "));
 
  printf("\nThank you, %s.  You entered %d\n", astring, anumber);
 
  while (getyn("\nDo you want to go again? [Y/n]")) {
     anumber = getnum("Enter some kind of integer: ");
     strcpy(astring, getstring("Enter your name: "));
 
     printf("\nThank you, %s.  You entered %d\n", astring, anumber);
   }
 
   printf("\nBye.\n");
 
  return (0);
}
#include <stdio.h>
#include <string.h>
#include <myfuncs.h>

int anumber;
char astring[255];

int
main ()
{
  printf ("This is the first time I've tried to '#include' my library!\n\n");

  anumber = getnum("Enter some kind of integer: ");
  strcpy(astring, getstring("Enter your name: "));

  printf("\nThank you, %s.  You entered %d\n", astring, anumber);

  while (getyn("\nDo you want to go again? [Y/n]")) {
     anumber = getnum("Enter some kind of integer: ");
     strcpy(astring, getstring("Enter your name: "));

     printf("\nThank you, %s.  You entered %d\n", astring, anumber);
   }

   printf("\nBye.\n");

  return (0);
}

CODE SUMMARY (from myfuncs.h):

C++ Syntax (Toggle Plain Text)
/* will act as the buffer into which user's response will be stored */
char lineofinput[255];
 
/* grabs a string from the command prompt */
char
getstring (char strquestion[255])
{
  /* reset */
  char lineofinput[255];
 
  if (strlen (strquestion))
    printf ("%s", strquestion);
 
  fgets (lineofinput, sizeof (lineofinput), stdin);
 
  /* while we get an empty response */
  while (strlen (lineofinput) == 1)
    {
      if (strlen (strquestion) == 1)
         printf ("Empty answers not permitted.  Please try again: ");
 
      return (getstring (lineofinput));
    }
 
  return (sprintf("%s", lineofinput));
}
/* will act as the buffer into which user's response will be stored */
char lineofinput[255];

/* grabs a string from the command prompt */
char
getstring (char strquestion[255])
{
  /* reset */
  char lineofinput[255];

  if (strlen (strquestion))
    printf ("%s", strquestion);

  fgets (lineofinput, sizeof (lineofinput), stdin);

  /* while we get an empty response */
  while (strlen (lineofinput) == 1)
    {
      if (strlen (strquestion) == 1)
         printf ("Empty answers not permitted.  Please try again: ");

      return (getstring (lineofinput));
    }

  return (sprintf("%s", lineofinput));
}

MY COMPILER:
tommy@city-it ~/cdevel
$ gcc -v
Reading specs from /usr/lib/gcc-lib/i686-pc-cygwin/3.3.3/specs
Configured with: /gcc/gcc-3.3.3-3/configure --verbose --prefix=/usr --exec-prefi
x=/usr --sysconfdir=/etc --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --enable-languages=c,ada,c++,d,f77,java,objc,
pascal --enable-nls --without-included-gettext --enable-libgcj --with-system-zlib --enable-interpreter --enable-threads=posix --enable-java-gc=boehm --enable-sjlj-exceptions --disable-version-specific-runtime-libs --disable-win32-registry
Thread model: posix
gcc version 3.3.3 (cygwin special)

Attached Files

cquestion.zip (1.2 KB, 18 views)

atrixnet

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Apr 22nd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast

Well, your getstring returns a single char and not a char*.

(Toggle Plain Text)

/* grabs a string from the command prompt */
char
getstring (char strquestion[255])
{
  /* reset */
  char lineofinput[255];

  if (strlen (strquestion))
    printf ("%s", strquestion);

  fgets (lineofinput, sizeof (lineofinput), stdin);

  /* while we get an empty response */
  while (strlen (lineofinput) == 1)
    {
      if (strlen (strquestion) == 1)
         printf ("Empty answers not permitted.  Please try again: ");

      return (getstring (lineofinput));
    }

  return (sprintf("%s", lineofinput));
}

But what you attempt to return is more worrisome.

You may want to take a peek at this.

Dave Sinkula

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long time no c

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast

Quote originally posted by Dave Sinkula ...

Well, your getstring returns a single char and not a char*.

Yes but how do I change that?

Quote ...

But what you attempt to return is more worrisome.

I'm sorry? What do you mean?

Quote ...

You may want to take a peek at this.

Unfortunately that isn't providing me with any answers to the question I've asked. Remember I'm a total newbie? Please help me out here by guiding me with a little easier terms to understand.

Thanks for responding to me!

atrixnet

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast"

>Yes but how do I change that?
I would think it would be obvious:

(Toggle Plain Text)

char *
getstring (char strquestion[255])

>I'm sorry? What do you mean?
sprintf returns the number of characters printed, not a string of any sort, which is what your use of getstring suggests. You could return lineofinput, and that would satisfy the type system, but then you would have problems because lineofinput is a local variable and is destroyed when the function returns. A much better solution would be to pass a pointer to the buffer to getstring. Then you can return a pointer to the buffer with no problem:

C++ Syntax (Toggle Plain Text)
#include <stdio.h>
 
char *getstring ( char buffer[], int size )
{
  if ( fgets ( buffer, size, stdin ) == NULL )
    return NULL;
 
  return buffer;
}
 
int main ( void )
{
  char buffer[BUFSIZ];
 
  if ( getstring ( buffer, sizeof buffer ) != NULL )
    printf ( "%s\n", buffer );
 
  return 0;
}
#include <stdio.h>

char *getstring ( char buffer[], int size )
{
  if ( fgets ( buffer, size, stdin ) == NULL )
    return NULL;

  return buffer;
}

int main ( void )
{
  char buffer[BUFSIZ];

  if ( getstring ( buffer, sizeof buffer ) != NULL )
    printf ( "%s\n", buffer );

  return 0;
}

>Unfortunately that isn't providing me with any answers to the question I've asked.
Perhaps not the question you asked now. If we give you a link (Dave or I in particular), we think you need the information whether you asked for it or not.

>Please help me out here by guiding me with a little easier terms to understand.
You read book. Use reference. It help make code good.

Narue

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast

>>Yes but how do I change that?
>I would think it would be obvious:

Seriously? I just started messing with C a few days ago. I've only ever programmed in Perl and Python. The example you provided works but I still have no idea why... I'll continue to research it, but I thought the point of this board was to get help with things, not get cryptic responses that provide more questions than I started with.

So far I'm very disappointed with the quality of help I've received. It's showing me how weak the community is around C and C++ whereas the community around python and perl leaves you guys looking like... well... words that shouldn't be uttered in public foura.

And please don't tell me, "well if you love perl so much why don't you just go away"... That is so below what I hoped you'd prove to be -helpful, friendy.

(Toggle Plain Text)

char *
getstring (char strquestion[255])

Like I said -works great but means nothing to me.

>sprintf returns the number of characters printed, not a string of any sort, which is what your use of getstring suggests. You could return lineofinput, and that would satisfy the type system, but then you would have problems because lineofinput is a local variable and is destroyed when the function returns. A much better solution would be to pass a pointer to the buffer to getstring. Then you can return a pointer to the buffer with no problem:

C++ Syntax (Toggle Plain Text)
#include <stdio.h>
 
char *getstring ( char buffer[], int size )
{
  if ( fgets ( buffer, size, stdin ) == NULL )
    return NULL;
 
  return buffer;
}
 
int main ( void )
{
  char buffer[BUFSIZ];
 
  if ( getstring ( buffer, sizeof buffer ) != NULL )
    printf ( "%s\n", buffer );
 
  return 0;
}
#include <stdio.h>

char *getstring ( char buffer[], int size )
{
  if ( fgets ( buffer, size, stdin ) == NULL )
    return NULL;

  return buffer;
}

int main ( void )
{
  char buffer[BUFSIZ];

  if ( getstring ( buffer, sizeof buffer ) != NULL )
    printf ( "%s\n", buffer );

  return 0;
}

Thanks this is good information, but still doesn't /explain/ anything, like what the "*" does and where you get "BUFSIZ".

>>Unfortunately that isn't providing me with any answers to the question I've asked.
>Perhaps not the question you asked now. If we give you a link (Dave or I in particular), we think you need the information whether you asked for it or not.

OK.

>>Please help me out here by guiding me with a little easier terms to understand.
>You read book. Use reference. It help make code good.

I really can't believe you just said that. I'm already working out of a book. Dare I ask if you know of any other places I could receive better help with C than this?

atrixnet

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast

Quote originally posted by atrixnet ...

where you get "BUFSIZ"

Wait, sorry I forgot BUFSIZ is in the faq you showed me, but not "*".

atrixnet

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast

"*" are pointers they point to a memory address.
Dave and Narue are not trying to be mean and cryptic. They are just trying to get you to work things out on your own. Most of us fell that it is a disservice to tell you everything and you not find it out on your own.

prog-bman

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast

Am I to understand then that there's no way for a function to return a true string in C

aka - return("Hello, my name is Simon");

atrixnet

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast"

Of course there is. Like dave and prelude saud you have to use the char* type.
e.g

C++ Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
 
char *getSomeString(void);
 
int main(void)
{
    char mainString[strlen(getSomeString()) + 1];
    strcpy(mainString,getSomeString());
    printf("%s",mainString);
    getchar();
}
 
char *getSomeString(void)
{
    return "Some String";
}
#include <stdio.h>
#include <string.h>

char *getSomeString(void);

int main(void)
{
    char mainString[strlen(getSomeString()) + 1];
    strcpy(mainString,getSomeString());
    printf("%s",mainString);
    getchar();
}

char *getSomeString(void)
{
    return "Some String";
}

Now I think I did the printf right I am a C++ man

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Apr 23rd, 2005

Re: total newb - "passing arg 2 of `strcpy' makes pointer from integer without a cast

Quote originally posted by prog-bman ...

Of course there is. Like dave and prelude saud you have to use the char* type.
e.g
C++ Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
 
char *getSomeString(void);
 
int main(void)
{
    char mainString[strlen(getSomeString()) + 1];
    strcpy(mainString,getSomeString());
    printf("%s",mainString);
    getchar();
}
 
char *getSomeString(void)
{
    return "Some String";
}
#include <stdio.h> #include <string.h> char *getSomeString(void); int main(void) { char mainString[strlen(getSomeString()) + 1]; strcpy(mainString,getSomeString()); printf("%s",mainString); getchar(); } char *getSomeString(void) { return "Some String"; }
Now I think I did the printf right I am a C++ man

Ok but i'm still in the dark, I'm sorry. If you say char *getSomeString... you aren't really returning a string, you're returning a pointer right? DOH!

And is it bad to say...

C++ Syntax (Toggle Plain Text)
char mainString[] = getSomeString();
char mainString[] = getSomeString();

My Oreilly book says...

Quote ...

C has a special shorthand for initializing strings: Surround the string with double quotes to simplify initialization...
C++ Syntax (Toggle Plain Text)
char name[] = "Sam";
char name[] = "Sam";
The dimension of name is 4 because C allocates a place for the '\0' character that ends the string.

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