c - Unable to start the int correctly and keep the number back from the function -

first @ sorry english, try best.

well, here's problem, making c program learning, program students manager, wanted add final function in user prompted id remove , after inserting id student eliminate database, problem is... when data inserted in first case there's added subroutine automatically adds id , int in struct,problem shows random int number "43405" or thought start integer 1, problem when function re-called again id 1 , don't work.

p.d:i read of guys told me make code more readable, can give me nice "tutorial" or make that?

function:

int insertar_notas(struct alumnos notas[20], int n,int id_alumno){       char resp[3];      system("cls");     puts("\n \a insercion del alumno\n");      while (!strstr(resp,"no")){           fflush(stdin);             printf("\nel id de este alumno sera: %d\n", id_alumno);             notas[n].id=id_alumno;             id_alumno++;             puts("\ndime el nombre del alumno\n");             scanf("%10s", notas[n].alumno );             system("cls");             fflush(stdin);             puts("\ndime el apellido del alumno\n");             scanf("%10s", notas[n].apellido );             system("cls");             puts("\ndime la primera nota trimestral del alumno[1.23]\n");             scanf("%f", &notas[n].nota1 );             system("cls");             puts("\ndime la segunda nota trimestral del alumno[1.23]\n");             scanf("%f", &notas[n].nota2 );             system("cls");             puts("\ndime la tercera nota trimestral del alumno[1.23]\n");             scanf("%f", &notas[n].nota3 );             n++;             system("cls");             puts("\nquieres volver insertar otro?[si|no]\n");             scanf("%3s", resp);             strlwr(resp);      }      return n;      return id_alumno;     }     

main more info:

int main (void){  int menu = 0, n = 0, id_alumno;     struct alumnos notas[20];   puts("\n<><><>bienvenido al recuento de notas de la escuela<><><>\n");  puts("\nque deseas hacer?\n");    while (menu != 5){        puts("\n1)insertas las notas de un alumno\n2)ver todas las notas\n3)ver las notas de un alumno\n4)modificar notas\n5)salir\n");         scanf("%d", &menu);          switch(menu){                     case 1:                          n=insertar_notas(notas,n,id_alumno);                         break; 

c uses pass value, make id_alumno modifiable need pass pointer:

int insertar_notas(struct alumnos notas[20], int n,int *id_alumno) { // id_alumno pointer int inside function       char resp[3];      system("cls");     puts("\n \a insercion del alumno\n");      while (!strstr(resp,"no")){           fflush(stdin);             printf("\nel id de este alumno sera: %d\n", *id_alumno);  // use * access value             notas[n].id=id_alumno;             (*id_alumno)++;  // use * access value. ++ has higher precedence *, need parenthesis around *id_alumno            ... 

and in call main:

                    n=insertar_notas(notas, n, &id_alumno);  // address-of id_alumno 

also, need initialize id_alumno in main:

int menu = 0, n = 0, id_alumno = 1;