Elements of a Structure Not Saving - c

Question

I've been trying to do a leaderboard program for school, but I've noticed that the program overwrites the first player when trying to add new ones.
Am I doing something wrong?
The code accepts the players just fine, but opposed to adding new players to the leader board it just overwrites the first one completely.
#include <stdio.h>
int number,i,key,newscore,a;
struct playerdata
{
char fname[50],lname[50];
int id,score;
}playerstats[5];
void welcome()
{
printf("\nWelcome to the leaderboard, challenger!");
printf("\nPlease select an option:");
printf("\n1-Add 5 players at a time\n2-Display all stats\n3-Update score\n4-Show player ranking\n5-Add 1 player");
printf("\n\n");
scanf("%d",&number);
switch(number)
{
case 1:
fillplayer();
break;
case 2:
displaystats();
break;
case 3:
updatescore();
break;
case 4:
playerranking();
break;
case 5:
addplayer();
break;
default:
printf("\nThis option is invalid");
}
}
void fillplayer() //read player info//
{
for(int i=0;i<5;i++)
{
printf("\nPlease enter your first name.");
scanf("%s", &playerstats[i].fname);
printf("\nPlease enter your last name.");
scanf("%s", &playerstats[i].lname);
printf("Please enter your player ID (Any random 4 digit number)");
scanf("%d",&playerstats[i].id);
printf("\n Please enter your score");
scanf("%d",&playerstats[i].score);
}
}
void displaystats() //Output player info//
{
printf("\nFirstName\tLast Name\tID\tScore\t");
for(int i=0;i<5;i++)
{
printf("\n%s\t\t%s\t\t%d\t\t%d",playerstats[i].fname,playerstats[i].lname,playerstats[i].id,playerstats[i].score);
}
}
void addplayer() //read one player's info//
{
printf("\nPlease enter your first name.");
scanf("%s", &playerstats[i].fname);
printf("\nPlease enter your last name.");
scanf("%s", &playerstats[i].lname);
printf("Please enter your player ID (Any random 4 digit number)");
scanf("%d",&playerstats[i].id);
printf("\n Please enter your score");
scanf("%d",&playerstats[i].score);
}
int searchplayer(void)
{
printf("\nEnter your player ID");
scanf("%d", &key);
{
if (playerstats[i].id=key)
{
return a;
}
else
{
return -1;
}
}
}
void updatescore()
{
a=searchplayer();
if (playerstats[i].id==key)
{
printf ("\nYour ID is%d", playerstats[i].id);
printf("\nEnter your new high score");
scanf("%d",&newscore);
if (newscore>playerstats[i].score)
{
playerstats[i].score=newscore;
printf("Score successfully changed to %d", newscore);
}
else
{
printf("\nThis score is less than your current highscore, the high score shall not be changed");
}
}
else
{
printf("\nInvalid ID");
}
}
void playerranking()
{
printf("\n not done");
}
int main()
{
for(int i=0;i<999;i++)
{
welcome();
}
return 0;
}

Answer 1

You have a local loop counter i inside the function main() and some other function.
You have a (not explicitly initialised) global variable i which is used inside other functions.
They are not the same.
You never change the global i, which is e.g. used in the relevant function addplayer().
To solve I recommend to:
define to yourself the meaning and use of the global variable
name it accordingly
introduce some way of changing it, maybe more options in the menu
use it as parameter to called functions
also use it in the function which adds 5 players at once (or that will always overwrite the same first five), i.e. use the sum of global "current" and local loop counter
quite hard, but probably what you want: use the global via pointer parameter in functions which are supposed to change it; e.g. especially the add5 function
consider all the globals; generally try to avoid globals, they got you into the trouble you are currently experiencing