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Function Details : setvbuf

intsetvbuf(FILE * stream,char * buffer,int mode,size_t size) ;

Return Type : int

Integer type (typically 4 bytes, -2,147,483,648 to 2,147,483,647)
Read about return values of setvbuf function .

1st Parameter Type : FILE *

Pointer to FILE structure for file operations

1st Parameter

Pointer to the `FILE` stream whose buffering mode is to be set.

2nd Parameter Type : char *

String pointer (array of characters)

2nd Parameter

Pointer to a user-provided buffer to be used for stream I/O. If `buffer` is `NULL`, the function allocates an internal buffer if necessary.

3rd Parameter Type : int

Integer type (typically 4 bytes, -2,147,483,648 to 2,147,483,647)

3rd Parameter

The buffering mode to set for the stream: `_IOFBF` (full buffering), `_IOLBF` (line buffering), or `_IONBF` (no buffering).

4th Parameter Type : size_t

Platform-specific unsigned type for array indices and memory sizes.

4th Parameter

The size of the buffer in bytes, if `buffer` is not `NULL`.

Read more about parameters of setvbuf in parameters section
The setvbuffunction in C language Sets a specific buffer and buffering mode for the given stream.
The setvbuf function allows you to specify the buffering mode and buffer size for a stream. It can be used to optimize I/O operations by controlling how data is buffered before being read from or written to a device.
The setvbuffunction takes 4 parameters:
  • •
    FILE * `stream`: Pointer to the `FILE` stream whose buffering mode is to be set.
  • •
    char * `buffer`: Pointer to a user-provided buffer to be used for stream I/O. If `buffer` is `NULL`, the function allocates an internal buffer if necessary.
  • •
    int `mode`: The buffering mode to set for the stream: `_IOFBF` (full buffering), `_IOLBF` (line buffering), or `_IONBF` (no buffering).
  • •
    size_t `size`: The size of the buffer in bytes, if `buffer` is not `NULL`.
Sets the buffering mode and buffer size for the specified `FILE` stream. The mode can be full buffering (`_IOFBF`), line buffering (`_IOLBF`), or no buffering (`_IONBF`). If `buffer` is `NULL`, an internal buffer is used. Returns `0` on success or a nonzero value on failure.
The setvbuf function return value :
  • Returns 0 on success, or a non-zero value if an invalid value is given for mode or if the request cannot be honored

Output

This example sets a custom fully buffered buffer for a file stream using setvbuf.