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std::atof

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< cpp‎ | string‎ | byte

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C++
 
Biblioteca cordas
Strings terminadas
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Null-terminated strings
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Cadeias de bytes
Multibyte cordas
Cordas de largura
Classes
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Classes
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Cordas de terminação nula de bytes
Funções
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Functions
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Manipulação personagem
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Character manipulation
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Conversões para formatos numéricos
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Conversions to numeric formats
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Manipulação de cadeia
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String manipulation
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Exame String
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String examination
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Manipulação de memória
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Memory manipulation
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Diversos
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Miscellaneous
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Definido no cabeçalho <cstdlib>
double atof( const char *str );
Interpreta um valor de ponto flutuante em uma seqüência de bytes apontado por str.
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Interprets an floating point value in a byte string pointed to by str.
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Função descarta quaisquer caracteres em branco (como determinado pela std::isspace()) até que caráter não-primeiro espaço é encontrada. Em seguida, ele toma como caracteres possível para formar uma representação de ponto flutuante válido e os converte em valor de ponto flutuante. O valor de ponto flutuante válido pode ser um dos seguintes:
Original:
Function discards any whitespace characters (as determined by std::isspace()) until first non-whitespace character is found. Then it takes as many characters as possible to form a valid floating point representation and converts them to floating point value. The valid floating point value can be one of the following:
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  • expressão ponto decimal flutuante. Consiste nas seguintes partes:
    Original:
    decimal floating point expression. It consists of the following parts:
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  • (opcional) mais ou de menos
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    (opcional) plus or minus sign
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  • seqüência não vazia de dígitos decimais, opcionalmente contendo um caractere de ponto decimal (define significand)
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    nonempty sequence of decimal digits optionally containing a decimal point character (defines significand)
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  • (opcional) e ou E seguiu com menos opcionais ou sinal de mais e não vazio seqüência de dígitos decimais (define expoente)
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    (opcional) e or E followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent)
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  • binário expressão de ponto flutuante. Consiste nas seguintes partes:
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    binary floating point expression. It consists of the following parts:
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  • (opcional) mais ou de menos
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    (opcional) plus or minus sign
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  • 0x or 0X
  • seqüência não vazia de dígitos hexadecimais opcionalmente contendo um caractere de ponto decimal (define significand)
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    nonempty sequence of hexadecimal digits optionally containing a decimal point character (defines significand)
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  • (opcional) p ou P seguiu com menos opcionais ou sinal de mais e não vazio seqüência de dígitos hexadecimais (define expoente)
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    (opcional) p or P followed with optional minus or plus sign and nonempty sequence of hexadecimal digits (defines exponent)
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  • infinito expressão. Consiste nas seguintes partes:
    Original:
    infinity expression. It consists of the following parts:
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  • (opcional) mais ou de menos
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    (opcional) plus or minus sign
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  • INF ou INFINITY ignorando o caso
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    INF or INFINITY ignoring case
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  • não-um número-expressão. Consiste nas seguintes partes:
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    not-a-number expression. It consists of the following parts:
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  • (opcional) mais ou de menos
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    (opcional) plus or minus sign
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  • NAN ou NAN(' char_sequence ) ignorando o caso da parte NAN. Char_sequence' só pode conter caracteres alfanuméricos. O resultado é uma tranquila NaN valor de ponto flutuante.
    Original:
    NAN or NAN(char_sequence) ignoring case of the NAN part. char_sequence can only contain alphanumeric characters. The result is a quiet NaN floating point value.
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Índice

[editar] Parâmetros

str -
ponteiro para o byte string terminada em nulo para ser interpretado
Original:
pointer to the null-terminated byte string to be interpreted
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[editar] Valor de retorno

double valor correspondente ao conteúdo do str em caso de sucesso. Se o valor convertido cai fora do alcance do tipo de retorno, o valor de retorno é indefinido. Se nenhuma conversão pode ser executada, é devolvido 0.0.
Original:
double value corresponding to the contents of str on success. If the converted value falls out of range of the return type, the return value is undefined. If no conversion can be performed, 0.0 is returned.
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[editar] Exemplo

Esta seção está incompleta
Motivo: sem exemplo

[editar] Veja também
converte uma seqüência de byte para um valor de ponto flutuante
Original:
converts a byte string to a floating point value
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(função) [edit]
Documentação C para atof
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