float a,b,c;
char o,w;
main()
{
do
{
clrscr();
printf("\t\t*** CALCULATOR ***\n\n\t");
printf("1 -> Arithmetic Calculation\n\n\t");
printf("2 -> Trigonometric & Logical calculations\n");
scanf("\n%c",&o);
switch(o)
{
case '1':
ari();
break;
case '2':
trig();
break;
default:
printf(" ");
}...