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switch statement

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Controle de fluxo
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Flow control
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Declarações execução condicional
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Conditional execution statements
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switch statement
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Exceptions
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Initialization
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Executa o código de acordo com o valor de um argumento integral
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Executes code according to value of an integral argument
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Utilizado onde um ou vários de muitos ramos de código precisa ser executado de acordo com um valor integral.
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Used where one or several out of many branches of code need to be executed according to an integral value.
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Índice

[editar] Sintaxe

switch ( expression ) {
case constant_expression1 :
statement1 (opcional)
case constant_expression2 :
statement2 (opcional)
... ... ...
case constant_expressionn :
statementn (opcional)
default: default_statement (opcional)

}

[editar] Explicação

expression deve ser uma expressão, convertível para um valor inteiro.
Original:
expression shall be an expression, convertible to an integer value.
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Todos os constant_expressions será expressões constantes, conversíveis para um valor inteiro, que é único nesta declaração switch
Original:
All constant_expressions shall be constant expressions, convertible to an integer value, which is unique within this switch statement
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Se o expression avaliada como um valor, igual ao valor de uma das constant_expressioni definido, o statementi (se presente) e todas as afirmações seguintes (excepto default_statement, se presente) são executados. Se o valor do expression não corresponde a nenhuma das constant_expressions, o default_statement é executado se presente.
Original:
If the expression evaluates to a value, equal to the value of one of the defined constant_expressioni, the statementi (if present) and all subsequent statements (except default_statement, if present) are executed. If the value of the expression does not match any of the constant_expressions, the default_statement is executed if present.
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pode ser usado. Nesse caso, a execução da instrução switch termina.
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It is useful to note, that if the execution of subsequent statements is undesirable, the
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[editar] Palavras-chave

switch, case, default

[editar] Exemplo

O código a seguir mostra vários casos de uso da chave declaração
Original:
The following code shows several usage cases of the switch statement
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#include <iostream>
 
int main()
{
    int i = 2;
    switch (i) {
        case 1: std::cout << "1";
        case 2: std::cout << "2";   //execution starts at this case label
        case 3: std::cout << "3";
        case 4:
        case 5: std::cout << "45";
                break;              //execution of subsequent statements is terminated
        case 6: std::cout << "6";
    }
 
    std::cout << '\n';
 
    switch (i) {
        case 4: std::cout << "a";
        default: std::cout << "d"; //there are no applicable constant_expressions 
                                   //therefore default_statement is executed
    }
 
    std::cout << '\n';
 
    switch (i) {
        case 4: std::cout << "a";  //nothing is executed
    }
}

Output:

2345
d