std::fread
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Definido en el archivo de encabezado <cstdio> | ||
std::size_t fread(void* buffer, std::size_t size, std::size_t count, std::FILE* stream ); | ||
Lee hasta objetos
count en el buffer matriz a partir de la corriente de entrada dado stream como si llamando std::fgetcsize veces para cada objeto, y el almacenamiento de los resultados, en el orden obtenido en las sucesivas posiciones de buffer, que se reinterpreta como una matriz de unsignedchar. El indicador de posición de fichero para el flujo se hace avanzar por el número de caracteres leídos .Original:
Reads up to
count objects into the array buffer from the given input stream stream as if by calling std::fgetcsize times for each object, and storing the results, in the order obtained, into the successive positions of buffer, which is reinterpreted as an array of unsignedchar. The file position indicator for the stream is advanced by the number of characters read.The text has been machine-translated via Google Translate.
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Si los objetos no son
TriviallyCopyable, el comportamiento no está definido .Original:
If the objects are not
TriviallyCopyable, the behavior is undefined.The text has been machine-translated via Google Translate.
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Si se produce un error, el valor resultante del indicador de posición del fichero para el flujo es
Original:
If an error occurs, the resulting value of the file position indicator for the stream is
The text has been machine-translated via Google Translate.
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indeterminada. Si un elemento parcial es leído, su valor es indeterminado
Original:
indeterminate. If a partial element is read, its value is indeterminate
The text has been machine-translated via Google Translate.
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Contenido |
[editar]Parámetros
| buffer | - | puntero hacia el objeto primero de la matriz para ser leído Original: pointer to the first object in the array to be read The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| size | - | tamaño de cada objeto en bytes Original: size of each object in bytes The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| count | - | el número de los objetos que se deben leer Original: the number of the objects to be read The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
[editar]Valor de retorno
Número de objetos leídos con éxito, lo que puede ser inferior a
count si una condición de error o de fin de archivo se produce . Original:
Number of objects read successfully, which may be less than
count if an error or end-of-file condition occurs. The text has been machine-translated via Google Translate.
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Si
size o count es cero, fread devuelve cero y no realiza ninguna otra acción .Original:
If
size or count is zero, fread returns zero and performs no other action.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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[editar]Ejemplo
Ejecuta este código
#include <iostream>#include <cstdio>#include <fstream>#include <vector>int main(){// prepare filestd::ofstream("test.txt")<<1<<' '<<2<<'\n';std::FILE* f =std::fopen("test.txt", "r"); std::vector<char> buf(4);// char is trivally copyable std::fread(&buf[0], sizeof buf[0], buf.size(), f); for(char n : buf)std::cout<< n; std::vector<std::string> buf2;// string is not trivially copyable// this would result in undefined behavior// std::fread(&buf2[0], sizeof buf2[0], buf2.size(), f);}
Salida:
1 2
[editar]Ver también
lee la entrada con formato desde stdin, una secuencia de archivo o un tampón Original: reads formatted input from stdin, a file stream or a buffer The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (función) | |
recibe una cadena de caracteres a partir de una secuencia de archivo Original: gets a character string from a file stream The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (función) | |
escribe en un archivo Original: writes to a file The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (función) | |
Documentación de C para fread | |
