Sorting strings by sorting an array of pointers

Question

1.00/5 (3 votes)

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(1).defines a pointer array as follows:

C

char *name[] ={"January", "February", "March", "April", "May",
"June", "July", "August", "September", "October", "November",
"December"};

where name is an array of pointers pointing to strings.

(2).sorts the month names in alphabetic order by arranging the values in the name array so that
name[0] points to “April ”, name[1] points to “August ”, and so on.

(3).prints the month names in alphabetic order, one name per line.

For step (2), you can use any sorting algorithm (such as the selection sort, bubble sort or quick sort
algorithm) to sort the name array. You can use the standard C library function strcmp() to
compare two strings. The function is declared in the system header file string.h as follows:
int strcmp(const char *s1, const char *s2);

It compares the two strings s1 and s2. It returns an integer less than, equal to, or greater than zero if
s1 is found, respectively, to be less than, to match, or be greater than s2.

i am really bad when it comes to programming so any help would be appreciated..thanks a lot:)

Posted 10-Mar-10 3:25am

bowww

Updated 14-Apr-10 1:31am

CPallini

v3

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Dave Kreskowiak · Answer 1 · 2010-03-10T03:28:00

Solution 1

This is a homework assignment. Just to be clear, we're not going to write your code for you.

What part of this are you hung up on?

Posted 10-Mar-10 3:28am

Dave Kreskowiak

CPallini · Answer 2 · 2010-04-14T01:35:00

Solution 19

bowww wrote:
i am really bad when it comes to programming so any help would be appreciated..thanks a lot

What about a career change?
:)

Posted 14-Apr-10 1:35am

CPallini

Gregory Gadow · Answer 3 · 2010-04-14T04:09:00

Solution 20

Since you can use any sorting algorithm, compare the strings in your head and provide coded output for the results. Problem solved.

Posted 14-Apr-10 4:09am

Gregory Gadow

bowww · Answer 4 · 2010-03-10T03:58:00

Solution 2

ok i dont know how to do the sorting in part 2.

Posted 10-Mar-10 3:58am

bowww

Eugen Podsypalnikov · Answer 5 · 2010-03-10T04:43:00

Try it :) :

C++

void SortNames(char** ppchNames, int iCount)
{
  for (int j = 0; j < iCount -1; j++) {
    for (int i = 0; i < iCount -1; i++) {
      if (0 < strcmp(ppchNames[i], ppchNames[i +1])) {
        char* pchTemp = ppchNames[i];
        ppchNames[i] = ppchNames[i +1];
        ppchNames[i +1] = pchTemp;
      }
    }
  }
}
 
void TheUsage() {
  char* names[] = {
    "bb",
    "gg",
    "hh",
    "aa"
  };
  SortNames(names, _countof(names));
}

Eugen Podsypalnikov · Answer 6 · 2010-03-10T05:13:00

Please try and validate it :) :

#include <iostream>
 
void SortNames(char** ppchNames, int iCount)
{
  for (int j = 0; j < iCount -1; j++) {
    for (int i = 0; i < iCount -1; i++) {
      if (0 < strcmp(ppchNames[i], ppchNames[i +1])) {
        char* pchTemp = ppchNames[i];
        ppchNames[i] = ppchNames[i +1];
        ppchNames[i +1] = pchTemp;
      }
    }
  }
}
 
void PrintNames(char** ppchNames, int iCount)
{
  for (int i = 0; i < iCount; i++) {
    cout << ppchNames[i] << "\n";
  }
}
 
int main()
{
  char* name[] = {
                  "January",
                  "February",
                  "March",
                  "April",
                  "May",
                  "June",
                  "July",
                  "August",
                  "September",
                  "October",
                  "November",
                  "December"
                 };
 
  cout << "-- before:" << "\n";
 
  PrintNames(name, _countof(name));
 
  SortNames(name, _countof(name));
 
  cout << "-- after:" << "\n";
 
  PrintNames(name, _countof(name));
 
  return 0;
}

Eugen Podsypalnikov · Answer 7 · 2010-03-10T05:33:00

Solution 7

Yes, it must be validated by you :)

Try to use #include <stdio.h> instead of #include <iostream>

and replace cout << with functions like printf(..)... :)

Posted 10-Mar-10 5:33am

Eugen Podsypalnikov

bowww · Answer 8 · 2010-03-10T05:44:00

C#

#include<stdio.h>
#include<math.h>
int i;
int j;
int iCount=0;
void SortNames(char** ppchNames, int iCount)
{
  for (int j = 0; j < iCount -1; j++) {
    for (int i = 0; i < iCount -1; i++) {
      if (0 < strcmp(ppchNames[i], ppchNames[i +1])) {
        char* pchTemp = ppchNames[i];
        ppchNames[i] = ppchNames[i +1];
        ppchNames[i +1] = pchTemp;
      }
    }
  }
}
void PrintNames(char** ppchNames, int iCount)
{
  for (int i = 0; i i < iCount; i++) {
   printf("%s\n", i);
  }
}
int main()
{
  char* name[] = {
                  "January",
                  "February",
                  "March",
                  "April",
                  "May",
                  "June",
                  "July",
                  "August",
                  "September",
                  "October",
                  "November",
                  "December"
                 };
    printf("%d\n", ppchNames);
  PrintNames(name, _countof(name));
  SortNames(name, _countof(name));
    printf("%d\n", ppchNames);

  PrintNames(name, _countof(name));
  return 0;
}

these are the errors:

VB

q11.c: In function ‘SortNames’:
q11.c:10: error: ‘for’ loop initial declaration used outside C99 mode
q11.c:11: error: ‘for’ loop initial declaration used outside C99 mode
q11.c: In function ‘PrintNames’:
q11.c:23: error: ‘for’ loop initial declaration used outside C99 mode
q11.c:23: error: syntax error before ‘i’
q11.c:23: error: syntax error before ‘)’ token
q11.c: In function ‘main’:
q11.c:31: error: stray ‘\226’ in program
q11.c:31: error: stray ‘\128’ in program
q11.c:31: error: stray ‘\156’ in program
q11.c:31: error: stray ‘\226’ in program
q11.c:31: error: stray ‘\128’ in program
q11.c:31: error: stray ‘\157’ in program
q11.c:31: error: ‘January’ undeclared (first use in this function)
q11.c:31: error: (Each undeclared identifier is reported only once
q11.c:31: error: for each function it appears in.)
q11.c:32: error: stray ‘\226’ in program
q11.c:32: error: stray ‘\128’ in program
q11.c:32: error: stray ‘\156’ in program
q11.c:32: error: stray ‘\226’ in program
q11.c:32: error: stray ‘\128’ in program
q11.c:32: error: stray ‘\157’ in program
q11.c:32: error: ‘February’ undeclared (first use in this function)
q11.c:33: error: stray ‘\226’ in program
q11.c:33: error: stray ‘\128’ in program
q11.c:33: error: stray ‘\156’ in program
q11.c:33: error: stray ‘\226’ in program
q11.c:33: error: stray ‘\128’ in program
q11.c:33: error: stray ‘\157’ in program
q11.c:33: error: ‘March’ undeclared (first use in this function)
q11.c:34: error: stray ‘\226’ in program
q11.c:34: error: stray ‘\128’ in program
q11.c:34: error: stray ‘\156’ in program
q11.c:34: error: stray ‘\226’ in program
q11.c:34: error: stray ‘\128’ in program
q11.c:34: error: stray ‘\157’ in program
q11.c:34: error: ‘April’ undeclared (first use in this function)
q11.c:35: error: stray ‘\226’ in program
q11.c:35: error: stray ‘\128’ in program
q11.c:35: error: stray ‘\156’ in program
q11.c:35: error: stray ‘\226’ in program
q11.c:35: error: stray ‘\128’ in program
q11.c:35: error: stray ‘\157’ in program
q11.c:35: error: ‘May’ undeclared (first use in this function)
q11.c:36: error: stray ‘\226’ in program
q11.c:36: error: stray ‘\128’ in program
q11.c:36: error: stray ‘\156’ in program
q11.c:36: error: stray ‘\226’ in program
q11.c:36: error: stray ‘\128’ in program
q11.c:36: error: stray ‘\157’ in program
q11.c:36: error: ‘June’ undeclared (first use in this function)
q11.c:37: error: stray ‘\226’ in program
q11.c:37: error: stray ‘\128’ in program
q11.c:37: error: stray ‘\156’ in program
q11.c:37: error: stray ‘\226’ in program
q11.c:37: error: stray ‘\128’ in program
q11.c:37: error: stray ‘\157’ in program
q11.c:37: error: ‘July’ undeclared (first use in this function)
q11.c:38: error: stray ‘\226’ in program
q11.c:38: error: stray ‘\128’ in program
q11.c:38: error: stray ‘\156’ in program
q11.c:38: error: stray ‘\226’ in program
q11.c:38: error: stray ‘\128’ in program
q11.c:38: error: stray ‘\157’ in program
q11.c:38: error: ‘August’ undeclared (first use in this function)
q11.c:39: error: stray ‘\226’ in program
q11.c:39: error: stray ‘\128’ in program
q11.c:39: error: stray ‘\156’ in program
q11.c:39: error: stray ‘\226’ in program
q11.c:39: error: stray ‘\128’ in program
q11.c:39: error: stray ‘\157’ in program
q11.c:39: error: ‘September’ undeclared (first use in this function)
q11.c:40: error: stray ‘\226’ in program
q11.c:40: error: stray ‘\128’ in program
q11.c:40: error: stray ‘\156’ in program
q11.c:40: error: stray ‘\226’ in program
q11.c:40: error: stray ‘\128’ in program
q11.c:40: error: stray ‘\157’ in program
q11.c:40: error: ‘October’ undeclared (first use in this function)
q11.c:41: error: stray ‘\226’ in program
q11.c:41: error: stray ‘\128’ in program
q11.c:41: error: stray ‘\156’ in program
q11.c:41: error: stray ‘\226’ in program
q11.c:41: error: stray ‘\128’ in program
q11.c:41: error: stray ‘\157’ in program
q11.c:41: error: ‘November’ undeclared (first use in this function)
q11.c:42: error: stray ‘\226’ in program
q11.c:42: error: stray ‘\128’ in program
q11.c:42: error: stray ‘\156’ in program
q11.c:42: error: stray ‘\226’ in program
q11.c:42: error: stray ‘\128’ in program
q11.c:42: error: stray ‘\157’ in program
q11.c:43: error: ‘December’ undeclared (first use in this function)
q11.c:44: error: ‘ppchNames’ undeclared (first use in this function)

Eugen Podsypalnikov · Answer 9 · 2010-03-10T06:10:00

And now ? :)

#include <stdio.h>
  
void SortNames(char** ppchNames, int iCount)
{
  int i,j;
  for (j = 0; j < iCount -1; j++) {
    for (i = 0; i < iCount -1; i++) {
      if (0 < strcmp(ppchNames[i], ppchNames[i +1])) {
        char* pchTemp = ppchNames[i];
        ppchNames[i] = ppchNames[i +1];
        ppchNames[i +1] = pchTemp;
      }
    }
  }
}
  
void PrintNames(char** ppchNames, int iCount)
{
  int i;
  for (i = 0; i < iCount; i++) {
    printf("%s\n", ppchNames[i]);
  }
}
  
int main()
{
  char* name[] = {
                  "January",
                  "February",
                  "March",
                  "April",
                  "May",
                  "June",
                  "July",
                  "August",
                  "September",
                  "October",
                  "November",
                  "December"
                 };
 
  printf("-- before:\n");
 
  PrintNames(name, _countof(name));
 
  SortNames(name, _countof(name));
 
  printf("-- after:\n");
 
  PrintNames(name, _countof(name));
 
  return 0;
}

bowww · Answer 10 · 2010-03-10T06:16:00

it still gives me:

VB

q11.c: In function ‘SortNames’:
q11.c:8: error: ‘lt’ undeclared (first use in this function)
q11.c:8: error: (Each undeclared identifier is reported only once
q11.c:8: error: for each function it appears in.)
q11.c:8: error: syntax error before ‘;’ token
q11.c:8: error: syntax error before ‘)’ token
q11.c:11: error: ‘pchTemp’ undeclared (first use in this function)
q11.c: At top level:
q11.c:15: error: syntax error before ‘}’ token
q11.c: In function ‘main’:
q11.c:28: error: stray ‘\226’ in program
q11.c:28: error: stray ‘\128’ in program
q11.c:28: error: stray ‘\156’ in program
q11.c:28: error: stray ‘\226’ in program
q11.c:28: error: stray ‘\128’ in program
q11.c:28: error: stray ‘\157’ in program
q11.c:28: error: ‘January’ undeclared (first use in this function)
q11.c:29: error: stray ‘\226’ in program
q11.c:29: error: stray ‘\128’ in program
q11.c:29: error: stray ‘\156’ in program
q11.c:29: error: stray ‘\226’ in program
q11.c:29: error: stray ‘\128’ in program
q11.c:29: error: stray ‘\157’ in program
q11.c:29: error: ‘February’ undeclared (first use in this function)
q11.c:30: error: stray ‘\226’ in program
q11.c:30: error: stray ‘\128’ in program
q11.c:30: error: stray ‘\156’ in program
q11.c:30: error: stray ‘\226’ in program
q11.c:30: error: stray ‘\128’ in program
q11.c:30: error: stray ‘\157’ in program
q11.c:30: error: ‘March’ undeclared (first use in this function)
q11.c:31: error: stray ‘\226’ in program
q11.c:31: error: stray ‘\128’ in program
q11.c:31: error: stray ‘\156’ in program
q11.c:31: error: stray ‘\226’ in program
q11.c:31: error: stray ‘\128’ in program
q11.c:31: error: stray ‘\157’ in program
q11.c:31: error: ‘April’ undeclared (first use in this function)
q11.c:32: error: stray ‘\226’ in program
q11.c:32: error: stray ‘\128’ in program
q11.c:32: error: stray ‘\156’ in program
q11.c:32: error: stray ‘\226’ in program
q11.c:32: error: stray ‘\128’ in program
q11.c:32: error: stray ‘\157’ in program
q11.c:32: error: ‘May’ undeclared (first use in this function)
q11.c:33: error: stray ‘\226’ in program
q11.c:33: error: stray ‘\128’ in program
q11.c:33: error: stray ‘\156’ in program
q11.c:33: error: stray ‘\226’ in program
q11.c:33: error: stray ‘\128’ in program
q11.c:33: error: stray ‘\157’ in program
q11.c:33: error: ‘June’ undeclared (first use in this function)
q11.c:34: error: stray ‘\226’ in program
q11.c:34: error: stray ‘\128’ in program
q11.c:34: error: stray ‘\156’ in program
q11.c:34: error: stray ‘\226’ in program
q11.c:34: error: stray ‘\128’ in program
q11.c:34: error: stray ‘\157’ in program
q11.c:34: error: ‘July’ undeclared (first use in this function)
q11.c:35: error: stray ‘\226’ in program
q11.c:35: error: stray ‘\128’ in program
q11.c:35: error: stray ‘\156’ in program
q11.c:35: error: stray ‘\226’ in program
q11.c:35: error: stray ‘\128’ in program
q11.c:35: error: stray ‘\157’ in program
q11.c:35: error: ‘August’ undeclared (first use in this function)
q11.c:36: error: stray ‘\226’ in program
q11.c:36: error: stray ‘\128’ in program
q11.c:36: error: stray ‘\156’ in program
q11.c:36: error: stray ‘\226’ in program
q11.c:36: error: stray ‘\128’ in program
q11.c:36: error: stray ‘\157’ in program
q11.c:36: error: ‘September’ undeclared (first use in this function)
q11.c:37: error: stray ‘\226’ in program
q11.c:37: error: stray ‘\128’ in program
q11.c:37: error: stray ‘\156’ in program
q11.c:37: error: stray ‘\226’ in program
q11.c:37: error: stray ‘\128’ in program
q11.c:37: error: stray ‘\157’ in program
q11.c:37: error: ‘October’ undeclared (first use in this function)
q11.c:38: error: stray ‘\226’ in program
q11.c:38: error: stray ‘\128’ in program
q11.c:38: error: stray ‘\156’ in program
q11.c:38: error: stray ‘\226’ in program
q11.c:38: error: stray ‘\128’ in program
q11.c:38: error: stray ‘\157’ in program
q11.c:38: error: ‘November’ undeclared (first use in this function)
q11.c:39: error: stray ‘\226’ in program
q11.c:39: error: stray ‘\128’ in program
q11.c:39: error: stray ‘\156’ in program
q11.c:39: error: stray ‘\226’ in program
q11.c:39: error: stray ‘\128’ in program
q11.c:39: error: stray ‘\157’ in program
q11.c:40: error: ‘December’ undeclared (first use in this function)

Eugen Podsypalnikov · Answer 11 · 2010-03-10T09:00:00

Solution 11

Please copy the improved code above and try again :)

Posted 10-Mar-10 9:00am

Eugen Podsypalnikov

bowww · Answer 12 · 2010-03-10T09:19:00

Solution 12

i did and it still gives this bunch of errors :(

Posted 10-Mar-10 9:19am

bowww

bowww · Answer 13 · 2010-03-10T09:20:00

Solution 13

oh now it gives me this:

Undefined symbols:
"__countof", referenced from:
_main in ccbdcvAC.o
_main in ccbdcvAC.o
_main in ccbdcvAC.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

Posted 10-Mar-10 9:20am

bowww

Eugen Podsypalnikov · Answer 14 · 2010-03-10T09:39:00

Solution 14

Try to replace _countof(name) with sizeof(name)/sizeof(char*) :)

Posted 10-Mar-10 9:39am

Eugen Podsypalnikov

bowww · Answer 15 · 2010-03-10T09:48:00

ya i think it works now:) except that i should've used:

int strcmp(const char *s1, const char *s2);

It compares the two strings s1 and s2. It returns an integer less than, equal to, or greater than zero if
s1 is found, respectively, to be less than, to match, or be greater than s2.

thanks a lot for your efforts and trying to help. it is really sweet of u :)

Eugen Podsypalnikov · Answer 16 · 2010-03-10T10:01:00

Solution 16

The function strcmp(..) is already used,
see at the if line inside of SortNames(..) :)

Posted 10-Mar-10 10:01am

Eugen Podsypalnikov

bowww · Answer 17 · 2010-03-10T10:04:00

Solution 17

ya right found it :)
thanks a lot.
are you a programmer? i need help with my assignment if you can pleaseee.

Posted 10-Mar-10 10:04am

bowww

Sorting strings by sorting an array of pointers

17 solutions

Solution 1

Solution 19

Solution 20

Solution 2

Solution 3

Solution 5

Solution 7

Solution 8

Solution 9

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