Trying to write a bubble sort algorithm which sorts any data type and works similar to qsort in stdlib in C.
This is the Code ive written, compiling it gives me a "Segmentation Fault" error Tried compiling with -g for gdb debugging which gave way more errors
as: In function `testcmp':
(.text+0x21a): multiple definition of `testcmp'
/tmp/cc9ULHuO.o:new.c:(.text+0x12d): first defined here
as: In function `_fini':
(.fini+0x0): multiple definition of `_fini'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_info): relocation 0 has invalid symbol index 7
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_info): relocation 1 has invalid symbol index 8
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_info): relocation 2 has invalid symbol index 9
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 0 has invalid symbol index 4
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 1 has invalid symbol index 4
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 2 has invalid symbol index 5
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 3 has invalid symbol index 5
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o:(.fini+0x0): first defined here
as: In function `bsort':
(.text+0x148): multiple definition of `bsort'
/tmp/cc9ULHuO.o:new.c:(.text+0x5b): first defined here
as: In function `data_start':
(.data+0x0): multiple definition of `__data_start'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 1 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 2 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 3 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 4 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 5 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 6 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 7 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 8 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 9 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 10 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 11 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 12 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 13 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 14 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 15 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 16 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 17 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 18 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 19 has invalid symbol index 21
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_line): relocation 0 has invalid symbol index 2
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o:(.data+0x0): first defined here
as: In function `data_start':
(.data+0x8): multiple definition of `__dso_handle'
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtbegin.o:(.data+0x0): first defined here
as:(.rodata+0x0): multiple definition of `_IO_stdin_used'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o:(.rodata.cst4+0x0): first defined here
as: In function `_start':
(.text+0x0): multiple definition of `_start'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o:/build/buildd/eglibc-2.18/csu/../sysdeps/x86_64/start.S:118: first defined here
as: In function `main':
(.text+0x245): multiple definition of `main'
/tmp/cc9ULHuO.o:new.c:(.text+0x158): first defined here
as: In function `_init':
(.init+0x0): multiple definition of `_init'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_line): relocation 0 has invalid symbol index 4
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_line): relocation 1 has invalid symbol index 5
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o:/build/buildd/eglibc-2.18/csu/../sysdeps/x86_64/crti.S:64: first defined here
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtend.o:(.tm_clone_table+0x0): multiple definition of `__TMC_END__'
as:(.data+0x10): first defined here
/usr/bin/ld: error in as(.eh_frame); no .eh_frame_hdr table will be created.
collect2: error: ld returned 1 exit status
Anyways heres the Code for it
#include <stdio.h>
#include <stdlib.h>
static void swap(char *a, char *b, unsigned int width)
{
char tmp;
if (a != b)
{
while (width--)
{
tmp = *a;
*a++ = *b;
*b++ = tmp;
}
}
}
void bsort (void* base, size_t num, size_t size,int (*compar)(const void*,const void*))
{
char *lo, *hi;
unsigned int i,j;
if(num<2 || size == 0) return;
for(i = 1; i <= num; i++)
{
for(j = 1; j <= num - i - 1; j++)
{
lo = (char *)base + size * (j-1);
hi = (char *)base + size * j;
if( compar(lo, hi) > 0 )
swap( lo, hi, size);
}
}
}
int testcmp(char **a, char **b)
{
return strcmp(*a, *b);
}
typedef int (*b_compare)(const void *a, const void *b);
int main(int argc, char *argv[])
{
char *ass[] = {"nabsdb", "asdjkhasd", "asdasdk", "ierik"};
bsort(ass,4,sizeof(char *),(b_compare)testcmp);
return 0;
}
I'm guessing something to do with char pointers, I did search a lot and refereed a lot of questions on Stack Overflow itself, Help me out
What i got from gdb, not really used to using gdb much
(gdb) step
30 lo = (char *)base + size * (j-1);
(gdb) step
31 hi = (char *)base + size * j;
(gdb) print lo
$3 = 0x7fffffffe370 "d\a@"
(gdb) print *lo
$4 = 100 'd'
(gdb) step
33 if( compar(lo, hi) > 0 )
(gdb) step
testcmp (a=0x7fffffffe370, b=0x7fffffffe378) at new.c:41
41 return strcmp(*a, *b);
(gdb) step
__strcmp_ssse3 () at ../sysdeps/x86_64/multiarch/../strcmp.S:180
180 ../sysdeps/x86_64/multiarch/../strcmp.S: No such file or directory.
(gdb) step
181 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
183 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
184 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
205 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
206 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
207 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
208 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
209 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
210 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
211 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
212 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) step
233 in ../sysdeps/x86_64/multiarch/../strcmp.S
(gdb) bt
#0 __strcmp_ssse3 () at ../sysdeps/x86_64/multiarch/../strcmp.S:233
#1 0x0000000000400683 in testcmp (a=0x7fffffffe370, b=0x7fffffffe378)
at new.c:41
#2 0x000000000040060d in bsort (base=0x7fffffffe370, num=4, size=8,
compar=0x40065a <testcmp>) at new.c:33
#3 0x00000000004006cf in main (argc=1, argv=0x7fffffffe478) at new.c:49
(gdb)
The program most likely passes down to testcmp() a reference to NULL.
Dereferencing it then causes the segementation violation.
Btw: Arrays in C a 0-based. Accessing a C-arrays 1st element is done by using 0 as index.