Entry and output Problem

[liukinhei]

Hi! I have a question about showing my input.
First , I have to ask user how many names want to input
i need to use a (dynamic) array to get all the name
then, show it

However, the program didnt show the name after i input the name

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

#define merror()   {printf("memory allocation problem\n");exit(1);}

int main(void)
{
	char *buffer;
	char **buf;
	int num;
	int i, j;

	printf(" how many names will be entered : \n");
	fflush(stdout);
	fgets ( buffer, 10,  stdin );
    num = atoi (buffer);

    if (num <=0)
    {
       printf("empty input \n");
    }
    else if (num >10)
   {
       printf("input too long \n");
    }
     else if (num >0 && num <= 10)
    {
        printf("you will enter %d names \n", num);
    }

	for(i=0; i < num; i++)
	{
		for(j=0; j<21; j++)
		{
		      buf[j]=fgetc(stdin);
		      if (buf[j]=='\n') {
		        buf[j]='\0';
		        break;   /* break j-loop */
		      }
		    }/* end j-loop */

		    if (j==21)
		    {
		      printf("input too long\n");
		      while(fgetc(stdin)!='\n');
		      continue;   /* continue i-loop */
                                     }
   }

    printf("\nunsorted input:\n");
    for(i=0; i< num; i++)
    printf("%s\n", buf[i]);

	return 0;
}

[xuftugulus]

	char *buffer;
	char **buf;

You should allocate memory for those buffers as you state.
With your "hard-coded" sizes, buffer should be allocated to 10 bytes, buf to 'num' pointers to char. and every buf[i] to 21 bytes.
Do you understand how to perform memory allocation using the malloc function?