std::ptrdiff_t
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Definido no cabeçalho <cstddef> | ||
typedef/*implementation-defined*/ ptrdiff_t; | ||
std::ptrdiff_t é o tipo inteiro assinado do resultado da subtracção de dois ponteiros.
Original:
std::ptrdiff_t is the signed integer type of the result of subtracting two pointers.
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[editar]Notas
std::ptrdiff_t é usado para aritmética de ponteiro e indexação de matriz, se os valores negativos são possíveis. Programas que usam outros tipos, como int, pode falhar em, por exemplo, Sistemas de 64 bits em que o índice excede INT_MAX ou se se baseia em 32 bits aritmética modular.
Original:
std::ptrdiff_t is used for pointer arithmetic and array indexing, if negative values are possible. Programs that use other types, such as int, may fail on, e.g. 64-bit systems when the index exceeds INT_MAX or if it relies on 32-bit modular arithmetic.
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Ao trabalhar com o C + + recipiente biblioteca, o tipo adequado para a diferença entre iteradores é o difference_type membro typedef, que muitas vezes é sinônimo de std::ptrdiff_t.
Original:
When working with the C++ container library, the proper type for the difference between iterators is the member typedef difference_type, which is often synonymous with std::ptrdiff_t.
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Somente ponteiros para os elementos da mesma matriz (incluindo o ponteiro um após o final da matriz) podem ser subtraídos uns dos outros.
Original:
Only pointers to elements of the same array (including the pointer one past the end of the array) may be subtracted from each other.
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Se uma matriz é tão grande (maior do que os elementos PTRDIFF_MAX, mas menos do que SIZE_MAX bytes), que a diferença entre dois ponteiros não podem ser representados de forma std::ptrdiff_t, o resultado da subtracção de dois ponteiros tais é indefinido.
Original:
If an array is so large (greater than PTRDIFF_MAX elements, but less than SIZE_MAX bytes), that the difference between two pointers may not be representable as std::ptrdiff_t, the result of subtracting two such pointers is undefined.
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Para matrizes de caracteres mais curtos do que PTRDIFF_MAXstd::ptrdiff_t, actua como o duplicado assinado std::size_t: ele pode armazenar o tamanho da matriz de qualquer tipo e é, na maioria das plataformas, sinónimo de std::intptr_t).
Original:
For char arrays shorter than PTRDIFF_MAX, std::ptrdiff_t acts as the signed counterpart of std::size_t: it can store the size of the array of any type and is, on most platforms, synonymous with std::intptr_t).
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[editar]Exemplo
#include <cstddef>int main(){conststd::size_t N =100;int* a = new int[N];int* end = a + N;for(std::ptrdiff_t i = N; i>0;--i)*(end - i)= i; delete[] a; }
[editar]Veja também
tipo inteiro sem sinal retornado pelo operador sizeof Original: unsigned integer type returned by the sizeof operator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (typedef) | |
byte offset do início de um tipo padrão de disposição-membro especificado Original: byte offset from the beginning of a standard-layout type to specified member The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (função macro) | |
