collect string in loop and printout all the string outside loop - c

Question

I'm newbie here and there is some question that I want have some lesson from you guys.
For example:
#include <stdio.h>
#include<stdlib.h>
#include<ctype.h>
void main()
{
char name[51],selection;
do
{
printf("Enter name: ");
fflush(stdin);
fgets(name,51,stdin);
printf("Enter another name?(Y/N)");
scanf("%c",&selection);
selection=toupper(selection);
}while (selection=='Y');
//I want to printout the entered name here but dunno the coding
printf("END\n");
system("pause");
}
As I know when the loops perform will overwrite the variable then how I perform a coding that will printout all the name user entered?
I have already ask my tutor and he is ask me to use pointer, can anyone guide me in this case?

Answer 1

You've basically got two options, create a list of all the names, looping through each of them at the end, or concatenate all the names into a string as you read them, and print that whole buffer at the end. The first goes roughly like this:
char ch[2]="Y", names[100][52]; //store up to 100 50-char names (leaving space for \n and \0)
int x, nnames=0;
while(nnames<100 && *ch=='Y'){
fgets(names[nnames++], sizeof names[0], stdin); //since names is a 2d array, look
//only at the length of a row, (in this case, names[0])
fgets(ch, 2, stdin);
*ch = toupper(*ch);
}
for(x=0; x<nnames; x++)
//print names[x].
And the second goes roughly like this:
char names[100*52], *np=names, *ep=names+sizeof names; //an array, the position, and the end
char ch[2]="Y";
while(np<ep && *ch=='Y'){
fgets(np, ep-np, stdin); //read a name, and a newline into the buffer
//note how I use the difference between the end and the position to tell
//fgets the most it can possibly read
np+=strlen(np); //advance the position to the end of what we read.
//same deal with the y/n stuff...
}
printf("%s", names);
Notice the lack of loop at the end, because the whole string is stored in names.

Answer 2

Use a single string to get all names:
char allnames[1000] = "";
do {
//get name in fgets
selection = toupper(selection);
strcat(allnames, selection);
//Check for repetion
} while (/*there is repetion*/);
printf("%s", allnames);
You've to select the size of allnames suitably to store all names.

Answer 3

You can use a linked list to store all the entered names. All data structure books talk about linked list a lot.
#include <stdio.h>
#include <stdlib.h>
struct name_node
{
char name[100];
struct name_node *next;
};
struct name_node* add_name(struct name_node *first, const char *name)
{
struct name_node *p;
/* create our node */
p = (struct name_node*)malloc(sizeof(struct name_node));
strcpy(p->name, name);
p->next = NULL;
/* link our node to the tail */
if (first) {
for (; first->next; first = first->next);
first->next = p;
}
return p;
}
void print_names(struct name_node *first)
{
/* print names stored in the list */
for (; first; first = first->next) {
printf("%s\n", first->name);
}
}
/* free the memory we used */
void destroy_list(struct name_node *first)
{
if (first) {
if (first->next)
destroy_list(first->next);
free(first);
}
}
int main(void)
{
struct name_node *head = NULL;
struct name_node *node;
char name[100];
char selection;
do {
printf("Enter name: ");
fflush(stdin);
fgets(name, 51, stdin);
/* save the user input to a linked list */
/* save head if we don't have head */
node = add_name(head, name);
if (!head)
head = node;
printf("Enter another name?(Y/N)");
scanf("%c", &selection);
selection = toupper(selection);
}
while (selection == 'Y');
/* print the list if we have any data */
if (head)
print_names(head);
/* free the memory we used */
destroy_list(head);
printf("END\n");
system("pause");
return 0;
}