fread
- Updated2023-02-21
- 2 minute(s) read
fread
size_t fread (void *buffer, size_t elementSize, size_t numberOfElements, FILE *stream);
Purpose
Reads a block of data from the specified input stream then stores it in the specified buffer. The function returns the number of elements successfully read and advances the file position indicator by the number of bytes read, that is (number_ofElements*elementSize).
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Note If you have opened the file for read/write, you cannot call fread after a call to fwrite or any of the other file output functions without an intervening call to fflush. |
Parameters
| Input | ||
| Name | Type | Description |
| elementSize | size_t | Specifies the size in bytes of each element to be read. |
| numberOfElements | size_t | Specifies the number of elements to be read. If a read error occurs or end-of-file is reached, the number of elements actually read can be less than the number specified in this parameter. |
| stream | FILE * | Specifies the input stream from which data will be read. |
| Output | ||
| Name | Type | Description |
| buffer | void * | Contains the address of a buffer that receives the data read from the specified input stream. |
Return Value
| Name | Type | Description |
| elementsRead | size_t | Contains the number of elements successfully read. If an error occurs, fread returns 0 and sets errno to a nonzero value. |
Additional Information
Library: ANSI C Library
Include file: ansi_c.h
LabWindows/CVI compatibility: LabWindows/CVI 3.0 and later