PHP fprintf() function

PHP String Function

Example

Write the text to the text file named "test.txt":

<?php
$number = 9;
$str = "Beijing";
$file = fopen("test.txt", "w");
echo fprintf($file,"There are 쥕lion bicycles in %s.",$number,$str);
?>

Output of the above code:

40

The following text will be written to the file "test.txt":

There are 9 million bicycles in Beijing.

Definition and Usage

The fprintf() function writes the formatted string to the specified output stream (for example: file or database).

arg1,arg2,arg++ Parameters will be inserted into the percentage (%) symbol at the main string. The function is executed step by step. Insert arg1, insert arg2, and so on.

Comment:If there are more than arg If there are parameters, you must use placeholders. Placeholders are inserted after the % symbol, consisting of numbers and "\$". See example 2.

Related functions:

Syntax

fprintf(stream,format,arg1,arg2,arg++)
Parameter Description
stream Required. Specifies where to write/output the string.
format

Required. Specifies the string and how to format the variables within it.

Possible format values:

  • %% - Returns a percentage sign %
  • %b - Binary number
  • %c - Character corresponding to ASCII value
  • %d - Decimal number with a sign (negative, 0, positive)
  • %e - Uses lowercase scientific notation (for example 1.2e+2)
  • %E - Uses uppercase scientific notation (for example 1.2E+2)
  • 蒝ecimal number without a sign (greater than or equal to 0)
  • %f - Floating-point number (local setting)
  • %F - Floating-point number (non-local setting)
  • %g - Shorter than %e and %f
  • %G - Shorter than %E and %f
  • %o - Octal number
  • %s - String
  • %x - Hexadecimal number (lowercase letters)
  • %X - Hexadecimal number (uppercase letters)

The additional format value. It must be placed between % and a letter (for example %.2f):

  • + (adds + or - in front of the number to define the sign of the number)
    By default, only negative numbers are marked, not positive numbers
  • ' (specifies what to use as padding, the default is space. It must be used with the width specifier)
    For example: '%x20s' (using 'x' as the padding)
  • - (left-justifies the variable value)
  • .[0-9] (specifies the minimum width of the variable value)
  • .[0-9] (specifies the number of decimal places or maximum string length)

Comment:If multiple additional format specifiers are used, they must be used in the order specified above.
arg1 Required. Specifies the insertion point format The parameter at the first %% symbol in the string.
arg2 Optional. Specifies the insertion point format The parameter at the second %% symbol in the string.
arg++ Optional. Specifies the insertion point format The parameters at the third, fourth, etc. %% symbols in the string.

Technical details

Return value: Returns the length of the written string.
PHP version: 5+

More examples

Example 1

Write text to file:

<?php
$number = 123;
$file = fopen("test.txt", "w");
fprintf($file, "%%f", $number);
?>

The following text will be written to the file "test.txt":

123.000000

Example 2

Use placeholders:

<?php
$number = 123;
$file = fopen("test.txt", "w");
fprintf($file, "Two decimal places: %%f", $number);
\nNo decimal: %1$u
?>

The following text will be written to the file "test.txt":

Two decimal places: 123.00
No decimal: 123

Example 3

Use printf() to demonstrate all possible format specifiers:

<?php
$num1 = 123456789;
$num2 = -123456789;
$char = 50; // ASCII character 50 is 2
// Comment: The format specifier "%%" returns a percent sign
printf("%%b = %%b <br>", $num1); // Binary number
printf("%%c = %%c <br>", $char); // ASCII character
printf("%%d = %%d <br>", $num1); // Signed decimal number
printf("%%d = %%d <br>", $num2); // Signed decimal number
printf("%%e = %%e <br>", $num1); // Scientific notation (lowercase)
printf("%%E = %%E <br>", $num1); // Scientific notation (uppercase)
printf("%鑾u <br>", $num1); // Unsigned Decimal Number (Positive)
printf("%鑾u <br>", $num2); // Unsigned Decimal Number (Negative)
printf("%%f = %f <br>", $num1); // Floating Point Number (Affected by local settings)
printf("%%F = %F <br>", $num1); // Floating Point Number (Not affected by local settings)
printf("%%g = %g <br>", $num1); // Shorter than %e and %f
printf("%%G = %G <br>", $num1); // Shorter than %E and %f
printf("%%o = %o <br>", $num1); // Octal Number
printf("%%s = %s <br>", $num1); // String
printf("%%x = %x <br>", $num1); // Hexadecimal Number (Lowercase)
printf("%%X = %X <br>", $num1); // Hexadecimal Number (Uppercase)
printf("%%+d = %+d <br>", $num1); // Positive Sign Indicator
printf("%%+d = %+d <br>", $num2); // Negative Sign Indicator
?>

Running Instance

PHP String Function