
//常量的定义
let country:String = "中华人民共和国"
print("your country is " ,country)
//常量的特征是值不能发生改变
//country = "美利坚合众国"。 //报错
print("=============================")
//运算符
//算术运算符
var a:Int = 11
var b:Int = 4
print("a + b = ",a + b)
print("a - b = ",a - b)
print("a * b = ",a * b)
print("a / b = ",a / b)//两个整数相除仍然是整数。
print("a % b = ",a % b)
//其它语言中存在自增自减运算
//a++ //不能使用++和--的符号，如果要实现可以通过+=和-=来实现
a += 1
print("a = ",a)

print("--------------------------------")
print("a > b ? ",a > b)
print("a < b ? ",a < b)
print("a >= b ? ",a >= b)
print("a <= b ? ",a <= b)
print("a == b ? ",a == b)
print("a != b ? ",a != b)

print("=================================")
print(a > 12 && b == 4)
print(a > 12 || b == 4)
print(!(b >= 4))

print("---------------------------------")
print(a == 11 ? "a是11" : "a不是11")