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Full Discussion: C. To segmentation fault or not to segmentation fault, that is the question.
Top Forums Programming C. To segmentation fault or not to segmentation fault, that is the question. Post 303032348 by wisecracker on Friday 15th of March 2019 12:14:06 PM
Old 03-15-2019
C. To segmentation fault or not to segmentation fault, that is the question.
Oddities with gcc, 2.95.3 for the AMIGA and 4.2.1 for MY current OSX 10.14.1...

I am creating a basic calculator for the AMIGA ADE *NIX emulator in C as it does not have one.

Below are two very condensed snippets of which I have added the results inside the each code section.

IMPORTANT! This will NOT even compile on gcc 2.95.3 for the AMIGA, but WORKS correctly on OSX 10.14.1, gcc 4.2.1.
Code:
/* No_error gcc 4.2.1 demo. */

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

int NUM_1;
int NUM_2;
char CHARACTER;

int main(int argc, char *argv[])
{
    /* Conditional BEFORE _variables_! */
    if (argc <= 3)
    {
        printf("ERROR!\n\n");
        printf("Not enough arguments!\n");
        exit(1);
    }

    int NUM_1 = strtod(argv[1], NULL);
    int NUM_2 = strtod(argv[3], NULL);
    CHARACTER = *argv[2];

    printf("\n%i, %i, %c\n\n", NUM_1, NUM_2, CHARACTER);

    return(0);
}


/* ****************************************
     Results OSX 10.14.1, gcc 4.2.1...

Last login: Fri Mar 15 14:45:03 on ttys000
AMIGA:amiga~> cd Desktop/Code/C
AMIGA:amiga~/Desktop/Code/C> gcc noerror.c
AMIGA:amiga~/Desktop/Code/C> ./a.out
ERROR!

Not enough arguments!
AMIGA:amiga~/Desktop/Code/C> ./a.out 1 v
ERROR!

Not enough arguments!
AMIGA:amiga~/Desktop/Code/C> ./a.out 1 v 3

1, 3, v

AMIGA:amiga~/Desktop/Code/C> _

**************************************** */

ALSO IMPORTANT! This compiles and WORKS perfectly on the AMIGA but gives a segmentation fault on OSX 10.14.1, gcc 4.2.1.
Code:
/* Error gcc 4.2.1 demo. */

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

int NUM_1;
int NUM_2;
char CHARACTER;

int main(int argc, char *argv[])
{
    int NUM_1 = strtod(argv[1], NULL);
    int NUM_2 = strtod(argv[3], NULL);
    CHARACTER = *argv[2];

    /* Conditional AFTER _variables_! */
    if (argc <= 3)
    {
        printf("ERROR!\n\n");
        printf("Not enough arguments!\n");
        exit(1);
    }

    printf("\n%i, %i, %c\n\n", NUM_1, NUM_2, CHARACTER);

    return(0);
}

/* ****************************************

Last login: Fri Mar 15 15:48:37 on ttys000
AMIGA:amiga~> cd Desktop/Code/C
AMIGA:amiga~/Desktop/Code/C> gcc error.c
AMIGA:amiga~/Desktop/Code/C> ./a.out
Segmentation fault: 11
AMIGA:amiga~/Desktop/Code/C> ./a.out 1 r
Segmentation fault: 11
AMIGA:amiga~/Desktop/Code/C> ./a.out 1 r 6

1, 6, r

AMIGA:amiga~/Desktop/Code/C> _

**************************************** */

As you can see the second code gives a Segmentation fault: 11 on OSX 10.14.1, gcc 4.2.1 but compiles and works correctly on the AMIGA.

Can anyone explain why there is a SEGMENTATION FAULT when the if conditional statement is inside the 'main()' function to start with and the assignments set?
 

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LEARN ABOUT HPUX

sigemptyset

sigsetops(3C)															     sigsetops(3C)

NAME

       sigemptyset(), sigfillset(), sigaddset(), sigdelset(), sigismember() - initialize, manipulate, and test signal sets

SYNOPSIS

DESCRIPTION

       initializes the signal set pointed to by set, to exclude all signals supported by HP-UX.

       initializes the signal set pointed to by set, to include all signals supported by HP-UX.

       Applications  must  call  either or at least once for each object of type before using that object for anything else, including cases where
       the object is returned from a function (for example, the oset argument to -- see sigprocmask(2)).

       adds the signal specified by signo to the signal set pointed to by set.

       deletes the signal specified by signo from the signal set pointed to by set.

       tests whether the signal specified by signo is a member of the signal set pointed to by set.

RETURN VALUE

       Upon successful completion, returns a value of 1 if the specified signal is a member of the specified set, or a value of 0 if  it  is  not.
       The other functions return a value of 0 upon successful completion.  For all of the above functions, if an error is detected, a value of -1
       is returned and is set to indicate the error.

ERRORS

       and fail if the following is true:

	      [EINVAL]	     The value of the signo argument is out of range.

WARNINGS

       The above functions do not detect a bad address passed in for the set argument.	A segmentation fault is the most likely result.

AUTHOR

       and were derived from the

SEE ALSO

       sigaction(2), sigsuspend(2), sigpending(2), sigprocmask(2), signal(5).

STANDARDS CONFORMANCE

																     sigsetops(3C)
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