New Data is Replacing Older Data Instead Adding New Data in C - c

Question

I am making simple C program. This program should be able to store data in memory (not using database). But when i tested it, it can not store more than 1 data. Every time i store new data, the old one get replaced. I hope these screenshot could help you understand what i mean.
As you can see, i input first set of data. It shows up with no problem.
Then, i added second set of data. Where is the first data ? The No 2 Data supposed to be after the No 1 data. But the first data get lost at all.
This is my input code :
//this is function for the input
void masukan() {
n=n+1; //use n as index for the struct (mhsw)
printf("\n");
printf("Masukkan NIM : "); scanf("%s", mhsw[n].nim);
printf("Masukkan Nama : "); scanf("%s", mhsw[n].nama);
printf("Masukkan Golongan UKT : "); scanf("%d", &mhsw[n].golUKT);
mhsw[n].nominalUKT = nominal(mhsw[n].golUKT)*100000;
printf("");
}
//the nominal UKT = factorial of golUKT
int nominal(int n) {
int hasil = 0;
if (n == 1) return 15;
else {
hasil = ((n*n) + nominal(n-1));
return hasil;
}
}
This is my output code :
//this is for the output
void tampil() {
if (!kbhit()) {
printf("\n");
printf(" ===========================================================================\n");
printf(" DATA MAHASISWA \n");
printf("|====|================|====================|==============|=================|\n");
printf("| No | NIM | Nama | Golongan UKT | Nominal UKT |\n");
printf("|====|================|====================|==============|=================|\n");
for(i=0; i<n; i++); //to display record
{
printf("%5d", i);
printf("%17s", mhsw[i].nim);
printf("%20s", mhsw[i].nama);
printf("%15d", mhsw[i].golUKT);
printf("%18d", mhsw[i].nominalUKT);
printf("\n");
}
printf("|====|================|====================|==============|=================|\n");
printf("\n \nPencet sembarang tombol untuk kembali ke Home");
getch();
} else {
menu();
}
}
This is the whole code :
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <windows.h>
//global variable
struct mahasiswa
{
char nim[10];
char nama[50];
int golUKT;
long int nominalUKT;
};
struct mahasiswa mhsw[50];
int i, n, nim;
bool ada = false;
char carinim[10];
//prototype
void login();
void menu();
void gotoxY(int, int);
void loading();
void masukan();
int nominal(int);
void tampil();
void cari();
//main function
void main() {
login();
}
void login() {
char user[10], pass[10];
int x, y;
printf("Masukkan Username : "); scanf("%s", user);
printf("Masukkan Password : "); scanf("%s", pass);
x = strcmp(user, "admin");
y = strcmp(pass, "admin123");
if (x == 0 && y == 0) {
menu();
}
else {
system("cls");
printf("Gagal Login, Ulangi Proses\n");
login();
}
}
void menu()
{
int pilih;
system("cls");
printf(" ____________________________________________________\n");
printf("| Siukat Lite |\n");
printf("|____________________________________________________|\n");
printf("|_______________________Home_________________________|\n");
printf("| 1. Pendaftaran Mahasiswa |\n");
printf("| 2. Daftar Golongan UKT |\n");
printf("| 3. Cari NIM |\n");
printf("| 4. Cetak Data Siukat |\n");
printf("| Ketik sembarang nomor untuk keluar |\n");
printf("|____________________________________________________|\n");
printf("Masukkan Pilihan Nomor : ");
scanf("%d",&pilih);
switch(pilih)
{
case 1:
//loading();
printf("\nPendaftaran Mahasiswa");
masukan();
menu();
break;
case 2:
case 3:
printf("Cari NIM");
cari();
break;
case 4:
//loading();
printf("\nData Siukat");
tampil();
default:
menu();
}
}
void gotoxy (int x,int y)
{
HANDLE hConsoleOutput;
COORD dwCursorPosition;
dwCursorPosition.X = x;
dwCursorPosition.Y = y;
hConsoleOutput = GetStdHandle(STD_OUTPUT_HANDLE);
SetConsoleCursorPosition(hConsoleOutput,dwCursorPosition);
}
void loading() {
int a;
char x;
gotoxy(1,12);
for(a=0;a<=5;a++)
{
usleep(500000);
printf("*",x);
}
}
//for input record
void masukan() {
printf("\n");
printf("Masukkan NIM : "); scanf("%9s", mhsw[n].nim);
printf("Masukkan Nama : "); scanf("%49s", mhsw[n].nama);
printf("Masukkan Golongan UKT : "); scanf("%d", &mhsw[n].golUKT);
mhsw[n].nominalUKT = nominal(mhsw[n].golUKT)*100000;
printf("");
n=n+1;
}
int nominal(int n) {
int hasil = 0;
if (n == 1) return 15;
else {
hasil = ((n*n) + nominal(n-1));
return hasil;
}
}
//for find NIM
void cari() {
printf("\nMasukkan NIM :"); scanf("%s", carinim);
printf("\n");
if (!kbhit()) {
for(i=0; i<n; i++) {
if (strcmp(carinim, mhsw[i].nim) == 1) {
ada = true;
} else {
ada = false;
}
}
if(ada) {
printf("NIM : %s \n", mhsw[i].nim);
} else {
printf("Data Tidak Ditemukan");
}
} else {
menu();
}
}
//for showing the record
void tampil() {
if (!kbhit()) {
printf("\n");
printf(" ===========================================================================\n");
printf(" DATA MAHASISWA \n");
printf("|====|================|====================|==============|=================|\n");
printf("| No | NIM | Nama | Golongan UKT | Nominal UKT |\n");
printf("|====|================|====================|==============|=================|\n");
for(i=0; i<n; i++);
{
printf("%5d", i);
printf("%17s", mhsw[i].nim);
printf("%20s", mhsw[i].nama);
printf("%15d", mhsw[i].golUKT);
printf("%18d", mhsw[i].nominalUKT);
printf("\n");
}
printf("|====|================|====================|==============|=================|\n");
printf("\n \nPencet sembarang tombol untuk kembali ke Home");
getch();
} else {
menu();
}
}
Thanks for any help
UPDATE : i tried to put increment after the insertion and see the value of n. Still doesn't work. Here is some screenshot.
The value of n before insertion is still 0
The value of n after insertion, it incremented to 1. But the data doesn't get recorded at all.

Answer 1

You have a ; after your for inside tampil().
for(i=0; i<n; i++);
It's causing your loop body to be empty so nothing is printed inside tampil().
To protect against such mistakes use a good compiler gcc and enable all warnings (for gcc it's -Wall -Wextra). Ex. gcc outputs this helpful warning message:
1.c: In function ‘tampil’:
1.c:167:9: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation]
167 | for(i=0; i<n; i++);
| ^~~
1.c:168:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘for’
168 | {
| ^

Answer 2

It is due to the fact that you do the n = n+1 instruction before the insertion in masukan(). You must move this instruction at the end of the function.
When the program starts, the value of n is 0. When you insert a new set of values, you first increment n and store thus the values at index 1. The values at index 0 are the default values.
When you print the values, you print the values with index 0 to n-1. This doesn't include the value at index n that you just inserted.
By moving the increment of n at the end of the new value insertion, the first value set will be inserted at index position 0 and n is the number of values in the table. n is also the index of the after last values in the table. This is where you insert the next value after what you increment n.
EDIT: another error is a ; after the for(i=0; i<n; i++) in the tampil function. That is the reason one line is printed regardless of the value of n.