Conversion Specifiers for sprintf Parts of a specifier A conversion specifier consists of the following parts, in the given order: -
A percent sign %. -
One or more flags (optional). -
A numeric minimum field width (optional). -
A numeric precision (optional). The precision, if present, begins with a period. -
A conversion character, which determines the type of conversion that will take place, as well as the interpretation of the other parts of the conversion specifier. The - (minus) flag specifies left-justified output. By default, converted values are right-justified. If a numeric field (width or precision) is replaced with an * (asterisk), the value of the field is taken from the next argument in the argument list. Integer specifiers | Specifier | Description | Notes | | d , i | Signed decimal | + (plus) flag adds leading + to positive values. ' ' (space) flag adds a leading space if the first character of the converted value is not a + or - . | | u | Unsigned decimal | | | o | Unsigned octal | # flag forces leading . | | x , X | Unsigned hexadecimal | x specifier outputs a-f ; X outputs A-F . # flag forces leading 0x . | For all integer specifiers, numbers are padded with leading s to the length specified by the precision. The (zero) flag pads to the field width with s. The flag l before an integer specifier indicates that the value is to be converted as a C long or unsigned long type. The flag h before an integer specifier indicates that the value is to be converted as a C short or unsigned short type. The flag V indicates that the value is to be converted as a Perl integer type. String specifiers | Specifier | Description | Notes | | s | String | Precision specifies maximum number of characters output; assumed infinite if omitted. | | c | Character | Value is converted to unsigned decimal and then output as a character. | Floating-point specifiers | Specifier | Description | Notes | | f | Fixed-point | For all floating-point specifiers, the precision specifies the number of digits to the right of the decimal point (6 by default). The # flag forces a decimal point. | | e , E | Exponential notation | Value is converted to exponential notation, e.g. 1.234e-03 . E specifier gives uppercase E . | | g , G | Fixed-point or exponential | Value is converted as per f or e ( E in case of G ). e is used if the exponent resulting from the conversion is less than -4 or greater than or equal to the precision. Trailing zeros after the decimal point are discarded. | The rule for the g (or G ) specifier may seem complicated, but basically all it means is to use whichever of f or e (or E ) looks better. Other specifiers | Specifier | Description | Notes | | % | Percent sign | Outputs a % . | | p | Pointer | Address of Perl value is output in hexadecimal. | | n | Count | Outputs a count of the number of characters generated in the output so far into the next variable in the argument list. | The -w command line option can be helpful in debugging sprintf or printf formats that don't work. |
