Here's the same result using printf in Bash: $ printf "%s\n" helloīut you get a lot of features for that added complexity, and that's exactly why printf is well worth learning. For example, here's a simple echo statement in Bash: $ echo hello It's clearly popular, and yet many people seem to regard its syntax to be complex, especially compared to alternatives such as echo or print or cout. Since its inclusion in C, printf has been reimplemented in C++, Java, Bash, PHP, and quite probably in whatever your favorite (post-C) language happens to be. The term printf stands for "print formatted" and may have first appeared in the Algol 68 programming language. In going against the puzzling tradition of hiding printf from beginners, this article aims to introduce to the world the humble printf function and explain how it can be used in nearly any language. eBook: An introduction to programming with Bashīut once I turned the first page of intermediate lessons, I met printf, a cryptic, mysterious, and surprisingly flexible function.Try for free: Red Hat Learning Subscription.The argument for the precision field parameter then follows the argument for the value to be formatted. The required value is then provided by an argument (permissible types: BYTE, WORD, DWORD, USINT, UINT, UDINT). The precision field parameter specifies how many characters from the argument string are output.Ĭharacters exceeding the precision value are not output.Īll characters up to the final zero are output.Īn asterisk (*) can also be entered for the precision field parameter. The argument value is always rounded to the respective number of decimal places. The precision field parameter specifies the number of decimal places. If there are not enough digits, the string is filled with zeros from the left. The precision field parameter specifies how many decimal characters (digits) are output in the output string. If the dot is not followed by a value, the default precision value is used (see table). The precision field follows the dot (.) and contains a positive decimal value. The standard C prefix type can be activated by setting the global variable GLOBAL_FORMAT_HASH_PREFIX_TYPE in the program: GLOBAL_FORMAT_HASH_PREFIX_TYPE := HASHPREFIX_STDC Only in conjunction with b, B, o, O, x, X, otherwise the flag is ignored. The blank flag is also ignored if the left sign flag (+) was set at the same timeĪn IEC or standard C prefix is placed before the formatted value. Only in conjunction with e, E, f, F, d, D, otherwise the flag is ignored. The zero flag will also be ignored if the left-alignment flag (-) is additionally set. Only in conjunction with e, E, f, F, s, S, otherwise the flag is ignored. If this flag precedes the Width parameter, the resulting string is filled with zeros from the left until the required width is reached. The negative sign only appears for negative values. ![]() Only in conjunction with e, E, f, F, d,D, otherwise the flag is ignored. The formatted value is left aligned within the width aligned in parameter Width.Ĭan be used in conjunction with all types.įorces output of the positive sign for signed positive numbers. The flag field parameters specify the alignment of the formatted value, the output of signs, spaces and the binary/octal/hex prefixes. One or more flags can be specified in any desired order in the flag field. Reserved for future use.įloating point numbers in scientific notationġ The content of the REAL variable is returned as a binary, octal, hexadecimal or decimal string.Ģ The content of the signed types is returned as a binary, octal, hexadecimal or decimal string.ģ The REAL variable is converted to the LREAL type and then formatted. Lower case letters ('abcdef') are used for formatting. Upper case letters ('ABCDEF') are used for formatting. The sign only appears for negative values.Ĭharacters are output until the final zero or the precision field parameter has been reached. If the length of the formatted string exceeds the maximum permissible length of the resulting string, '#OVF' or '-#OVF' is returned.īYTE, WORD, DWORD, SINT, INT, DINT, USINT, UINT, UDINT If the variable transferred has an illegal value (NaN, Not-a-Number), '#QNAN' or '-#QNAN' is returned. '#INF' is returned for an infinite positive value and '-#INF' for an infinite negative value. The sign only appears for negative values. The number of digits after the decimal point depends on the required precision. The number of digits before the decimal point depends on the value of the floating point number. The string has the form dddd.dddd, (dddd are decimal numbers). ![]() Note that some type field parameters are case-sensitive.īYTE, WORD, DWORD, REAL 1,SINT 2, INT 2, DINT 2, USINT, UINT, UDINTīYTE, WORD, DWORD, SINT 2, INT 2, DINT 2, USINT, UINT, UDINT The type field contains an ASCII character, which specifies whether the associated argument is interpreted as a string, an integer or a floating point number.
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