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Update fread() clobber conditions #584

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colin-home merged 1 commit into from
Dec 1, 2018
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Update fread() clobber conditions #584

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2 changes: 1 addition & 1 deletion docs/c-runtime-library/reference/fread.md
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Expand Up @@ -47,7 +47,7 @@ See [\_doserrno, errno, \_sys\_errlist, and \_sys\_nerr](../../c-runtime-library

The **fread** function reads up to *count* items of *size* bytes from the input *stream* and stores them in *buffer*. The file pointer associated with *stream* (if there is one) is increased by the number of bytes actually read. If the given stream is opened in [text mode](../../c-runtime-library/text-and-binary-mode-file-i-o.md), Windows-style newlines are converted into Unix-style newlines. That is, carriage return-linefeed (CRLF) pairs are replaced by single linefeed (LF) characters. The replacement has no effect on the file pointer or the return value. The file-pointer position is indeterminate if an error occurs. The value of a partially read item cannot be determined.

When used on a text mode stream, if the amount of data requested (that is, *size* \* *count*) is greater than the internal **FILE** \* buffer size (by default this is 4096 bytes, configurable by using [setvbuf](../../c-runtime-library/reference/setvbuf.md)), stream data is copied directly into the user-provided buffer, and newline conversion is done in that buffer. Since the converted data may be shorter than the stream data copied into the buffer, data past *buffer*\[*return_value* \* *size*] (where *return_value* is the return value from **fread**) may contain unconverted data from the file. For this reason, we recommend you null-terminate character data at *buffer*\[*return_value* \* *size*] if the intent of the buffer is to act as a C-style string. See [fopen](fopen-wfopen.md) for details on the effects of text mode and binary mode.
When used on a text mode stream, if the amount of data requested (that is, *size* \* *count*) is greater than or equal to the internal **FILE** \* buffer size (by default this is 4096 bytes, configurable by using [setvbuf](../../c-runtime-library/reference/setvbuf.md)), stream data is copied directly into the user-provided buffer, and newline conversion is done in that buffer. Since the converted data may be shorter than the stream data copied into the buffer, data past *buffer*\[*return_value* \* *size*] (where *return_value* is the return value from **fread**) may contain unconverted data from the file. For this reason, we recommend you null-terminate character data at *buffer*\[*return_value* \* *size*] if the intent of the buffer is to act as a C-style string. See [fopen](fopen-wfopen.md) for details on the effects of text mode and binary mode.

This function locks out other threads. If you need a non-locking version, use **_fread_nolock**.

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