Write a formatted string to a stream

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- PHP Manual
- String Functions
- Write a formatted string to a stream

# fprintf

(PHP 5, PHP 7, PHP 8)

fprintf — Write a formatted string to a stream

### Description

fprintf(resource `$stream`, string `$format`, mixed `...$values`): int

Write a string produced according to `format` to the stream resource specified by `stream`.

### Parameters

`stream`

  A file system pointer resource that is typically created using fopen().

`format`

  The format string is composed of zero or more directives: ordinary characters (excluding `%`) that are copied directly to the result and conversion specifications, each of which results in fetching its own parameter.

  A conversion specification follows this prototype: `%[argnum$][flags][width][.precision]specifier`.

  ##### Argnum

  An integer followed by a dollar sign `$`, to specify which number argument to treat in the conversion.

  Flags
  Flag | Description
  --- | ---
  `-` | Left-justify within the given field width; Right justification is the default
  `+` | Prefix positive numbers with a plus sign `+`; Default only negative are prefixed with a negative sign.
  `` (space) | Pads the result with spaces. This is the default.
  `0` | Only left-pads numbers with zeros. With `s` specifiers this can also right-pad with zeros.
  `'`(char) | Pads the result with the character (char).

  ##### Width

  Either an integer that says how many characters (minimum) this conversion should result in, or `*`. If `*` is used, then the width is supplied as an additional integer value preceding the one formatted by the specifier.

  ##### Precision

  A period `.` optionally followed by either an integer or `*`, whose meaning depends on the specifier:

  - For `e`, `E`, `f` and `F` specifiers: this is the number of digits to be printed after the decimal point (by default, this is 6).
  - For `g`, `G`, `h` and `H` specifiers: this is the maximum number of significant digits to be printed.
  - For `s` specifier: it acts as a cutoff point, setting a maximum character limit to the string.

  > Note: If the period is specified without an explicit value for precision, 0 is assumed. If `*` is used, the precision is supplied as an additional integer value preceding the one formatted by the specifier.

  Specifiers
  Specifier | Description
  --- | ---
  `%` | A literal percent character. No argument is required.
  `b` | The argument is treated as an integer and presented as a binary number.
  `c` | The argument is treated as an integer and presented as the character with that ASCII.
  `d` | The argument is treated as an integer and presented as a (signed) decimal number.
  `e` | The argument is treated as scientific notation (e.g. 1.2e+2).
  `E` | Like the `e` specifier but uses uppercase letter (e.g. 1.2E+2).
  `f` | The argument is treated as a float and presented as a floating-point number (locale aware).
  `F` | The argument is treated as a float and presented as a floating-point number (non-locale aware).
  `g` | General format. Let P equal the precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. Then, if a conversion with style E would have an exponent of X: If P > X ≥ −4, the conversion is with style f and precision P − (X + 1). Otherwise, the conversion is with style e and precision P − 1.
  `G` | Like the `g` specifier but uses `E` and `f`.
  `h` | Like the `g` specifier but uses `F`. Available as of PHP 8.0.0.
  `H` | Like the `g` specifier but uses `E` and `F`. Available as of PHP 8.0.0.
  `o` | The argument is treated as an integer and presented as an octal number.
  `s` | The argument is treated and presented as a string.
  `u` | The argument is treated as an integer and presented as an unsigned decimal number.
  `x` | The argument is treated as an integer and presented as a hexadecimal number (with lowercase letters).
  `X` | The argument is treated as an integer and presented as a hexadecimal number (with uppercase letters).

  Warning

  The `c` type specifier ignores padding and width

  Warning

  Attempting to use a combination of the string and width specifiers with character sets that require more than one byte per character may result in unexpected results

  Variables will be co-erced to a suitable type for the specifier:

  Type Handling
  Type | Specifiers
  --- | ---
  string | `s`
  int | `d`, `u`, `c`, `o`, `x`, `X`, `b`
  float | `e`, `E`, `f`, `F`, `g`, `G`, `h`, `H`

`values`

### Return Values

Returns the length of the string written.

### Errors/Exceptions

As of PHP 8.0.0, a ValueError is thrown if the number of arguments is zero. Prior to PHP 8.0.0, a `E_WARNING` was emitted instead.

As of PHP 8.0.0, a ValueError is thrown if `[width]` is less than zero or bigger than `PHP_INT_MAX`. Prior to PHP 8.0.0, a `E_WARNING` was emitted instead.

As of PHP 8.0.0, a ValueError is thrown if `[precision]` is less than zero or bigger than `PHP_INT_MAX`. Prior to PHP 8.0.0, a `E_WARNING` was emitted instead.

As of PHP 8.0.0, a ArgumentCountError is thrown when less arguments are given than required. Prior to PHP 8.0.0, `false` was returned and a `E_WARNING` emitted instead.

### Changelog

Version | Description
--- | ---
8.0.0 | This function no longer returns `false` on failure.
8.0.0 | Throw a ValueError if the number of arguments is zero; previously this function emitted a `E_WARNING` instead.
8.0.0 | Throw a ValueError if `[width]` is less than zero or bigger than `PHP_INT_MAX`; previously this function emitted a `E_WARNING` instead.
8.0.0 | Throw a ValueError if `[precision]` is less than zero or bigger than `PHP_INT_MAX`; previously this function emitted a `E_WARNING` instead.
8.0.0 | Throw a ArgumentCountError when less arguments are given than required; previously this function emitted a `E_WARNING` instead.

### Examples

Example #1 fprintf(): zero-padded integers

    <?phpif (!($fp = fopen('date.txt', 'w'))) {    return;}fprintf($fp, "%04d-%02d-%02d", $year, $month, $day);// will write the formatted ISO date to date.txt?>

Example #2 fprintf(): formatting currency

    <?phpif (!($fp = fopen('currency.txt', 'w'))) {    return;}$money1 = 68.75;$money2 = 54.35;$money = $money1 + $money2;// echo $money will output "123.1";$len = fprintf($fp, '%01.2f', $money);// will write "123.10" to currency.txtecho "wrote $len bytes to currency.txt";// use the return value of fprintf to determine how many bytes we wrote?>

### See Also

- printf() - Output a formatted string
- sprintf() - Return a formatted string
- vprintf() - Output a formatted string
- vsprintf() - Return a formatted string
- vfprintf() - Write a formatted string to a stream
- sscanf() - Parses input from a string according to a format
- fscanf() - Parses input from a file according to a format
- number_format() - Format a number with grouped thousands
- date() - Format a Unix timestamp