Selection

判断选择

​If

if (boolean expression) {
执行内容
}

if (boolean expression)
//single statement

if 结构

If-else

if (boolean expression) {
    //do if true
} else {
    //do if false
}

if-else 结构

Multiple if-else

if (boolean expression) {
    //do stuff
} else if (boolean expr) {
    //do other stuff
} else {
    //do yet other stuff
}

Multiple if-else 结构（多种条件判断）

Switch

switch (value) {
    case val1:
        //do stuff
        break;
    case val2:
        //do other stuff
        break;
    default:
        //yet other stuff
}

Switch结构（不同case）

Switch with fall-through

switch (value) {
    case val1:
        //do stuff
    case val2:
        //do other stuff
        break;
    default:
        //yet other stuff
}

Switch with fall-through结构

Switch

• Value used for comparison must be an integer, char, or enumeration.

  • enumeration = identifier that maps to an integer

• When a matching case is found, code is executed until encountering a break. This can result in code for multiple cases executing (fall-through)

  • Tip: when debugging, check for missing or mistaken break statements