This C++ program uses a switch statement to allow the user to select calculating either the area of a triangle or the circumference of a circle. Based on the user's input, it will prompt for the appropriate values, perform the calculation, and display the result. It also includes an if/else statement to determine and display a letter grade based on a student's GPA.

1. #include <iostream.h>
#define phi 3.14
void main ()
{
int a;
float t,r,hasil,keliling;
cout<<"keterangan : " <<endl;
cout<<"Angka 1 untuk menghitung LUAS SEGITIGA " <<endl;
cout<<"Angka 2 Untuk Menghitung KELILING LINGKARAN " <<endl;
cout<<"Masukan Pilihan Anda = ";
cin>>a;
switch (a)
{
case 1:
{
cout<<"Menghitung Luas Segitiga" <<endl;
cout<<"masukan alas = ";
cin>>a;
cout<<"masukan tinggi = ";
cin>>t;
hasil=a*t/2;
cout<<"hasil ";
cout<<hasil;
break;
}
case 2:
{
cout<<"menghitung keliling lingkaran" <<endl;
cout<<"masukan jari-jari = ";
cin>>r;
keliling = phi * r * r;
cout<<"keliling lingkaran = ";
cout<<keliling;
break;
}
}
}
#include <iostream.h>
void main ()
{
float nilai;
cout<<"masukan Nilai IPK ";
cin>>nilai;
if (nilai>=3)
cout<<"A" <<endl;
else if(nilai<3&&nilai>=2)
cout<<"B" <<endl;
else
cout<<"C";
}