String selection sort fuction

[paranoidgnu]

#include <stdio.h>
#include <string.h>
int get_min_range(const char *list, int first,int last)
{
	int i, j, min_pos;
	for (i=first; i<=last; i++) {  
		min_pos = i;
		for (j=first; j<=last; j++) 
		if( strcmp( list[j], list[i]) < 0)
			min_pos = j;
		}
	printf("%d---\n", list[min_pos]);
	return(min_pos);	
}

void select_sort(const char *list, int n)		
{	
	int fill, index_of_min;	
	char temp[20];
	
	for (fill=0;fill<n-1;fill++){		
		index_of_min = get_min_range(list, fill, n-1);
		
		/*Exchange elements at fill and index_of_min					*/
		if(fill != index_of_min){
			strcpy(temp, list[index_of_min]);
			strcpy(list[index_of_min],list[fill]);
			strcpy(list[fill],temp);
		}
	}
}
int main(void)
{
	char list[20];
	printf("Enter word> ");
	scanf("%s", list);
	select_sort(list,strlen(list));	
	return(0);
}

The code is not working.I couldn't found where is the problem.It gives Segmentation fault,

[claudiu]

Use a debugger and trace the values. Most likely you are forgetting the '\0' when you are allocating memory.

[paranoidgnu]

Use a debugger and trace the values. Most likely you are forgetting the '\0' when you are allocating memory.

I installed Nemiver.When it calls select_sort funtion, it gives "Target received a signal: SIGSEGV, Segmentation fault"
And also compiler gives

make 9.4.1.o (in directory: /home/mustafa/Documents/My_C_Programs/programmings)
cc -c -o 9.4.1.o 9.4.1.c
9.4.1.c: In function ‘get_min_range’:
9.4.1.c:9:3: warning: passing argument 1 of ‘strcmp’ makes pointer from integer without a cast
/usr/include/string.h:143:12: note: expected ‘const char *’ but argument is of type ‘char’
9.4.1.c:9:3: warning: passing argument 2 of ‘strcmp’ makes pointer from integer without a cast
/usr/include/string.h:143:12: note: expected ‘const char *’ but argument is of type ‘char’
9.4.1.c: In function ‘select_sort’:
9.4.1.c:26:4: warning: passing argument 2 of ‘strcpy’ makes pointer from integer without a cast
/usr/include/string.h:128:14: note: expected ‘const char * __restrict__’ but argument is of type ‘char’
9.4.1.c:27:4: warning: passing argument 1 of ‘strcpy’ makes pointer from integer without a cast
/usr/include/string.h:128:14: note: expected ‘char * __restrict__’ but argument is of type ‘char’
9.4.1.c:27:4: warning: passing argument 2 of ‘strcpy’ makes pointer from integer without a cast
/usr/include/string.h:128:14: note: expected ‘const char * __restrict__’ but argument is of type ‘char’
9.4.1.c:28:4: warning: passing argument 1 of ‘strcpy’ makes pointer from integer without a cast
/usr/include/string.h:128:14: note: expected ‘char * __restrict__’ but argument is of type ‘char’
Compilation finished successfully.

[claudiu]

That's because you are calling strcmp and strcpy incorrectly. Check their documentation pages. They take pointers as parameters not individual characters.

[paranoidgnu]

That's because you are calling strcmp and strcpy incorrectly. Check their documentation pages. They take pointers as parameters not individual characters.

It is described in an example(in book).Book gives a comparison(numeric to string) and says write the string selection sort function described in example.
I mean strcmp and strcpy from book's example...

[tabstop]

I think you need to decide if you want to exchange whole chunks of letters or just single letters. (Your comment suggests the second.) If you just want to swap single letters, then strcpy is the wrong tool for the job (you should just use equal sign). If you want to swap chunks, you will need to make sure that each chunk is \0 terminated (which you don't appear to do).

EDIT: The flip side of that is that the syntax you are using would be marvelous IF list were, not an array of chars, but an array of char* instead.

[claudiu]

Ok, if what you posted previously is from your book I suggest you set the book on fire and get another one. There are plenty of recommendations in the book thread on this forum.

If what you posted is your own work, then I suggest, like I said above, to look at the documentation pages for strcpy and strcmp and see the examples of their usage there.

[paranoidgnu]

Ok, if what you posted previously is from your book I suggest you set the book on fire and get another one. There are plenty of recommendations in the book thread on this forum.

If what you posted is your own work, then I suggest, like I said above, to look at the documentation pages for strcpy and strcmp and see the examples of their usage there.

Name of the book is Problem Solving and Program Design in C.
What will you suggest.Will I start coding from beginning or can it be corrected.

[paranoidgnu]

I have edited the code.It works well, but sometimes makes wrong sort.Compiler didn't give errors.But, I am not sure about code.

#include <stdio.h>
#include <string.h>
int get_min_range(const char *list, int first,int last);
void select_sort(char *list, int n);	
int main(void)
{
	char list[20];
	printf("Enter word> ");
	scanf("%s",list);
	select_sort(list,strlen(list));
	printf("%s", list);
	return(0);
}
int get_min_range(const char *list, int first,int last)
{
	int min_pos;
		min_pos = first;
			//if(strcmp(&list[last], &list[first]) < 0)
			if ( list[last] < list[first])
			min_pos = last;
	return(min_pos);
}

void select_sort(char *list, int n)	
{	
	int fill, index_of_min;	
	char temp[20];
	
	for (fill=0;fill<n;fill++){		
		index_of_min = get_min_range(list, fill, n-1);		
		/*Exchange elements at fill and index_of_min					*/
		if(fill != index_of_min){
			strncpy(temp, &list[index_of_min], 1);
			strncpy(&list[index_of_min], &list[fill], 1);
			strncpy(&list[fill], temp, 1);
		}
	}
}

[mike65535]

Can you supply examples of sorts that work and ones that don't?

[paranoidgnu]

Can you supply examples of sorts that work and ones that don't?

not working:

Enter word> asdfg
agdfs

working:

Enter word> deneme
deeemn

[iMalc]

It is wrong to use strcmp or strncpy inside the sorting algorithm or get_min_range here. You are not sorting strings, but sorting chars.

[tabstop]

Why does your get_min_range only look at the first and the last elements? What happens if your smallest element is somewhere in the middle?