Swift if...else语句

if语句后面可以跟一个可选的else语句，它在if语句布尔表达式为false时执行。

语法

Swift 4中if...else语句的语法如下 -

if boolean_expression {
   /* statement(s) will execute if the boolean expression is true */

} else {
   /* statement(s) will execute if the boolean expression is false */
}

如果布尔表达式的计算结果为true，那么将执行if代码块，否则将执行else代码块。

示例代码

var varA:Int = 100;

/* Check the boolean condition using if statement */
if varA < 20 {
   /* If condition is true then print the following */
   print("varA is less than 20");

} else {
   /* If condition is false then print the following */
   print("varA is not less than 20");
}

print("Value of variable varA is \\(varA)");

编译并执行上述代码时，会产生以下结果 -

varA is not less than 20
Value of variable varA is 100