In next program
1) I used "exit()" from "core.stdc.stdlib;" module, but someone
can say this isn't the D way to exit the program.
2) I used "goto", I heard from someone before that using "goto"
isn't good programming feature.
'''D
module proj07;
import std.stdio;
import std.algorithm;
import std.range;
import core.stdc.stdlib;
int main()
{
double x, y;
int choice;
new_again:
x=0;
y=0;
write("Enter a number: ");
readf(" %s\n", &x);
y=x;
writeln;
choice_again:
writeln("1) addition 2) subtraction 3)
multiplication 4) division 0) exit -1) new");
": ".write;
readf(" %s\n", &choice);
if(!only(1,2,3,4,0,-1).canFind(choice))
goto choice_again;
else if(choice==0)
exit(0);
else if(choice==-1)
goto new_again;
write("Enter a number: ");
readf(" %s\n", &x);
switch(choice){
case 1: y+=x; break;
case 2: y-=x; break;
case 3: y*=x; break;
case 4: y/=x; break;
default: break;}
y.writeln;
goto choice_again;
return 0;
}
'''
https://github.com/pascal111-fra/D/blob/main/proj07.d
