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swift中的下划线(_)用法
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//if循环中, 替代变量名来忽略对值的访问 | |
let base = 3 | |
let power = 10 | |
var answer = 1 | |
for _ in 1...power { | |
answer *= base | |
} | |
print("\(base) to the power of \(power) is \(answer)") | |
//switch的tuple, 匹配所有可能的值 | |
let somePoint = (1, 1) | |
switch somePoint { | |
case (0, 0): | |
print("(0, 0) is at the origin") | |
case (_, 0): | |
print("(\(somePoint.0), 0) is on the x-axis") | |
case (0, _): | |
print("(0, \(somePoint.1)) is on the y-axis") | |
case (-2...2, -2...2): | |
print("(\(somePoint.0), \(somePoint.1)) is inside the box") | |
default: | |
print("(\(somePoint.0), \(somePoint.1)) is outside of the box") | |
} | |
//函数定义时, 如果你不想为第二个及后续的参数设置外部参数名, 用一个下划线(_)代替一个明确的参数名。 | |
func someFunction(firstParameterName: Int, _ secondParameterName: Int) { | |
// function body goes here | |
// firstParameterName and secondParameterName refer to | |
// the argument values for the first and second parameters | |
} | |
someFunction(1, 2) |
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