C/C++ :: Swapping Like Function - Replace Player In A Team

I have a question about one function in my program. Write a function that will replace players in a team. New player gets in the game, and takes the place of one that leaves. Prototype of function is:

void replace(TEAM *p,PLAYER newplayer,int num)

where second parameter is new player, and the third is a jersey number of player who leaves the game.
Two structures are defined as:

typedef struct {
char name[25],surname[25];int number;
}PLAYER;
typedef struct {
char nameofteam[25];int numberofplayers;PLAYER *players;
}TEAM;

First I tried to read which player should get out, but that didnt work:

printf("which player should get out?
");
do {
scanf("%s",p->players.number)
} while(p->players.number);//Choose one of previously read players

Second thing is to read a new player and replace him with the chosen who leaves.