Conversion Formats

Each conversion character sequence results in fetching zero or more arguments. If insufficient arguments are provided for the format string, or if the format string is exhausted and arguments remain, the D compiler issues an appropriate error message. If an undefined conversion format is specified, the D compiler issues an appropriate error message. The conversion character sequences are:

a

The pointer or uintptr_t argument is printed as a kernel symbol name in the form module`symbol-name plus an optional hexadecimal byte offset. If the value does not fall within the range defined by a known kernel symbol, the value is printed as a hexadecimal integer.

c

The char, short, or int argument is printed as an ASCII character.

C

The char, short, or int argument is printed as an ASCII character if the character is a printable ASCII character. If the character is not a printable character, it is printed using the corresponding escape sequence as shown in Table 2–5.

d

The char, short, int, long, or long long argument is printed as a decimal (base 10) integer. If the argument is signed, it will be printed as a signed value. If the argument is unsigned, it will be printed as an unsigned value. This conversion has the same meaning as i.

e, E

The float, double, or long double argument is converted to the style [-]d.ddde±dd, where there is one digit before the radix character and the number of digits after it is equal to the precision. The radix character is non-zero if the argument is non-zero. If the precision is not specified, the default precision value is 6. If the precision is 0 and the # flag is not specified, no radix character appears. The E conversion format produces a number with E instead of e introducing the exponent. The exponent always contains at least two digits. The value is rounded up to the appropriate number of digits.

f

The float, double, or long double argument is converted to the style [-]ddd.ddd, where the number of digits after the radix character is equal to the precision specification. If the precision is not specified, the default precision value is 6. If the precision is 0 and the # flag is not specified, no radix character appears. If a radix character appears, at least one digit appears before it. The value is rounded up to the appropriate number of digits.

g, G

The float, double, or long double argument is printed in the style f or e (or in style E in the case of a G conversion character), with the precision specifying the number of significant digits. If an explicit precision is 0, it is taken as 1. The style used depends on the value converted: style e (or E) is used only if the exponent resulting from the conversion is less than -4 or greater than or equal to the precision. Trailing zeroes are removed from the fractional part of the result. A radix character appears only if it is followed by a digit. If the # flag is specified, trailing zeroes are not removed from the result.

i

The char, short, int, long, or long long argument is printed as a decimal (base 10) integer. If the argument is signed, it will be printed as a signed value. If the argument is unsigned, it will be printed as an unsigned value. This conversion has the same meaning as d.

o

The char, short, int, long, or long long argument is printed as an unsigned octal (base 8) integer. Arguments that are signed or unsigned may be used with this conversion. If the # flag is specified, the precision of the result will be increased if necessary to force the first digit of the result to be a zero.

p

The pointer or uintptr_t argument is printed as a hexadecimal (base 16) integer. D accepts pointer arguments of any type. If the # flag is specified, a non-zero result will have 0x prepended to it.

s

The argument must be an array of char or a string. Bytes from the array or string are read up to a terminating null character or the end of the data and interpreted and printed as ASCII characters. If the precision is not specified, it is taken to be infinite, so all characters up to the first null character are printed. If the precision is specified, only that portion of the character array that will display in the corresponding number of screen columns is printed. If an argument of type char * is to be formatted, it should be cast to string or prefixed with the D stringof operator to indicate that DTrace should trace the bytes of the string and format them.

S

The argument must be an array of char or a string. The argument is processed as if by the %s conversion, but any ASCII characters that are not printable are replaced by the corresponding escape sequence described in Table 2–5.

u

The char, short, int, long, or long long argument is printed as an unsigned decimal (base 10) integer. Arguments that are signed or unsigned may be used with this conversion, and the result is always formatted as unsigned.

wc

The int argument is converted to a wide character (wchar_t) and the resulting wide character is printed.

ws

The argument must be an array of wchar_t. Bytes from the array are read up to a terminating null character or the end of the data and interpreted and printed as wide characters. If the precision is not specified, it is taken to be infinite, so all wide characters up to the first null character are printed. If the precision is specified, only that portion of the wide character array that will display in the corresponding number of screen columns is printed.

x, X

The char, short, int, long, or long long argument is printed as an unsigned hexadecimal (base 16) integer. Arguments that are signed or unsigned may be used with this conversion. If the x form of the conversion is used, the letter digits abcdef are used. If the X form of the conversion is used, the letter digits ABCDEF are used. If the # flag is specified, a non-zero result will have 0x (for %x) or 0X (for %X) prepended to it.

Y

The uint64_t argument is interpreted to be the number of nanoseconds since 00:00 Universal Coordinated Time, January 1, 1970, and is printed in the following cftime(3C) form: “%Y %a %b %e %T %Z.” The current number of nanoseconds since 00:00 UTC, January 1, 1970 is available in the walltimestamp variable.

%

Print a literal % character. No argument is converted. The entire conversion specification must be %%.