Shell編程簡單實現四則運算

Shell編程簡單實現四則運算：

1. #!/bin/sh
2. main()
3. {
4. echo "#############################"
5. echo "## usage: num1 +/-/#// num2##"
6. echo "## example: 1 + 1 ##"
7. echo "## '*' is replaced by '#' ##"
8. echo "#############################"
9. while [ 1 ]
10. do
11. echo "## please select : ##"
12. echo "## 1.cal ##"
13. echo "## 0.exit ##"
14. read select
15. if [ "$select" = "1" ]
16. then
17. cal;
18. elif [ "$select" = "0" ]
19. then
20. break;
21. fi
22. done
23. }
24. cal()
25. {
26. echo "please enter number,as: number1 sign number2:"
27. read str
28. num1=`echo $str|cut -d' ' -f1`
29. num2=`echo $str|cut -d' ' -f3`
30. sign=`echo $str|cut -d' ' -f2`
31. case $sign in
32. +)
33. sum=`expr $num1 + $num2`;
34. echo "$num1 $sign $num2 = $sum";;
35. -)
36. sum=`expr $num1 - $num2`;
37. echo "$num1 $sign $num2 = $sum";;
38. \#)
39. sum=`expr $num1 \* $num2`;
40. echo "$num1 * $num2 = $sum";;
41. /)
42. sum=`expr $num1 / $num2`;
43. echo "$num1 $sign $num2 = $sum";;
44. *)
45. echo "your enter is wrong";;
46. esac
47. echo "please enter to continue"
48. read cto
49. }
50. main