shell_basic_math.xkx

#!/bin/zsh
# declare variable
a=7
b=2
c=2
echo "a:$a,b:$b,c:$c"
echo '================by (()) ========================'
echo "a+b:$((a+b))"
echo "a-b:$((a-b))"
echo "a*b:$((a*b))"
echo "a/b:$((a/b))"
echo "a%b:$((a%b))"
echo "a^b:$((a**b))"
echo "a<<1:$((a<<1))"
echo "a>>1:$((a>>1))"
echo "--a:$((--a))" # echo 6
# echo "a--:$((a--))" # echo 7 和 --a compare
echo "a:$a"
echo "a==b:$((a==b))"
echo "a==c:$((b==c))"
echo "a!=c:$((!b==c))"
echo '================by let ========================'
let sum=a-b
echo ${sum}
echo '================by bc ========================'
d=1.15
e=3.37
echo "d*e,两位小数"
echo "scale=2;$a*$b"|bc
echo "输入为十进制，输出为二进制:"
echo "ibase=10;obase=2;4*6"|bc
echo "计算平方和平方根:"
echo "10^2"|bc
echo "sqrt(100)"|bc

echo '================ handle float/double by awk ========================'
echo 5 3 | awk '{ printf "%0.4f\n" ,$1/$2}'