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[![Image 1: PHP String Reference Manual]( PHP String Reference Manual]( ## Example Write some text to a file named "test.txt": The above code will output: 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 a formatted string to a specified output stream (e.g., a file or database). arg1, arg2, ++ parameters will be inserted at the percent sign (%) in the main string. This function is executed step by step. At the first % symbol, arg1 is inserted, at the second % symbol, arg2 is inserted, and so on. **Note:** If there are more % symbols than arg parameters, you must use placeholders. Placeholders are inserted after the % symbol, consisting of a number and "$". See Example 2 for details. **Tip:** Related functions: [printf()]( [sprintf()]( [vprintf()]( [vsprintf()]( and [vfprintf()]( * * * ## 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 percent sign % * %b - Binary number * %c - Character corresponding to ASCII value * %d - Signed decimal number (negative, 0, positive) * %e - Using lowercase scientific notation (e.g., 1.2e+2) * %E - Using uppercase scientific notation (e.g., 1.2E+2) * %u - Unsigned decimal number (greater than or equal to 0) * %f - Floating-point number (locale-aware) * %F - Floating-point number (not locale-aware) * %g - Shorter of %e and %f * %G - Shorter of %E and %f * %o - Octal number * %s - String * %x - Hexadecimal number (lowercase) * %X - Hexadecimal number (uppercase) Additional format values. Must be placed between % and letter (e.g., %.2f): * + (Adds + or - before the number to indicate positivity or negativity. By default, only negative numbers are marked, positive numbers are not) * ' (Specifies what to use as padding, default is space. It must be used with the width specifier. E.g.: %"x20s" (uses "x" as padding)) * - (Left-aligns the variable value) * (Specifies the minimum width of the variable value) * . (Specifies the number of decimal places or maximum string length) **Note:** If multiple of the above format values are used, they must be used in the order specified above, not mixed up. | | _arg1_ | Required. Specifies the parameter to insert at the first % symbol in the format string. | | _arg2_ | Optional. Specifies the parameter to insert at the second % symbol in the format string. | | _arg++_ | Optional. Specifies the parameter to insert at the third, fourth, etc. % symbols in the format string. | ## Technical Details | Return Value: | Returns the length of the written string. | | --- | | PHP Version: | 5+ | * * * ## More Examples ## Example 1 Write some text to a file: The following text will be written to the file "test.txt": 123.000000 ## Example 2 Using placeholders: The following text will be written to the file "test.txt": With 2 decimals: 123.00 With no decimals: 123 ## Example 3 Use printf() to demonstrate all possible format values: <?php $num1 = 123456789; $num2 = -123456789; $char = 50; // The ASCII Character 50 is 2 // Note: The format value "%%" returns a percent sign printf("%%b = %b
",$num1); // Binary number printf("%%c = %c
",$char); // The ASCII Character printf("%%d = %d
",$num1); // Signed decimal number printf("%%d = %d
",$num2); // Signed decimal number printf("%%e = %e
",$num1); // Scientific notation (lowercase) printf("%%E = %E
",$num1); // Scientific notation (uppercase) printf("%%u = %u
",$num1); // Unsigned decimal number (positive) printf("%%u = %u
",$num2); // Unsigned decimal number (negative) printf("%%f = %f
",$num1); // Floating-point number (locale-aware) printf("%%F = %F
",$num1); // Floating-point number (not locale-aware) printf("%%g = %g
",$num1); // Shorter of %e and %f printf("%%G = %G
",$num1); // Shorter of %E and %f printf("%%o = %o
",$num1); // Octal number printf("%%s = %s
",$num1); // String printf("%%x = %x
",$num1); // Hexadecimal number (lowercase) printf("%%X = %X
",$num1); // Hexadecimal number (uppercase) printf("%%+d = %+d
",$num1); // Sign specifier (positive) printf("%%+d = %+d
",$num2); // Sign specifier (negative) ?> [Run Example »]( * * * [![Image 2: PHP String Reference Manual]( PHP String Reference Manual]( ```