NAME | C SYNOPSIS | DESCRIPTION | EXAMPLES | BUGS | RETURN VALUE | SEE ALSO | COLOPHON
PMPARSEUNITSSTR(3) Library Functions Manual PMPARSEUNITSSTR(3)
pmParseUnitsStr - parse units specification
#include <pcp/pmapi.h> int pmParseUnitsStr(const char *string, struct pmUnits *out, double *outMult, char **errMsg); cc ... -lpcp
pmParseUnitsStr is designed to encapsulate the interpretation of a units (dimension and scale) specification in command line switches for use by the PCP client tools. This function expects to be called with the unit/scale specifica‐ tion as string. This specification takes the general form pro‐ duced by pmUnitsStr(3). Briefly, the format allows /-separated divisor and dividend, each listing space-separated dimen‐ sions/scales along the space, time, and count axes. There are al‐ so a few extra possibilities: First, multiple equivalent sets of keywords are accepted for the time and space dimensions, insensitive to case. For example, "mi‐ croseconds", "microsecond", "microsec", "us" are considered syn‐ onymous, as are "kilobytes", "KB", "KiB", "kiloByte", and so on. Second, units may be offered in any order, e.g., ms kb count x 10^3 or count x 10^3 kb ms. They may not be repeated within the denominator or within the numerator. Each scale/unit keyword may be immediately followed by positive or negative exponents, e.g., ^-4. Third, numerical scaling factors may be supplied. These are fac‐ tored together with implicit scale conversions into the final out‐ Mult result. The out and outMult values must both be allocated before calling pmParseUnitsStr(3). If the conversion is successful, pmParseU‐ nitsStr returns 0, and fills in out and outMult with the unit/scales defined by the input parameter. If the argument strings could not be parsed, it returns a negative status code.
┌───────────────────────────────────┬────────────────┬─────────┐
│ string │ out │ outMult │
├───────────────────────────────────┼────────────────┼─────────┤
│ 2 count │ {0,1,0,0,0,0} │ 0.5 │
│ count / 7.5 nanosecond │ {0,1,-1,0,0,0} │ 7.5 │
│ 10 kilobytes / 2.5e2 count x 10^3 │ {1,-1,0,1,3,0} │ 25 │
│ millisecond / second^2 │ {0,0,-1,0,0,3} │ 1000 │
│ mib/s │ {1,0,-1,2,0,3} │ 1 │
└───────────────────────────────────┴────────────────┴─────────┘
For backward compatibility, this interface interprets several tra‐ ditional computer science interpretations of space units incor‐ rectly according to the International System of Units (SI) stan‐ dard. The accepted unit string - in either singular or plural form - and the pmParseUnitsStr interpretation for each are: megabyte (is re‐ ally mebibyte), gigabyte (is really gibibyte), terabyte (is really tebibyte), petabyte (is really pebibyte), exabyte (is really exbibyte), zettabyte (is really zebibyte) and yottabyte (is really yobibyte).
A zero status indicates success. A negative status indicates an error, in which case the errMsg pointer will contain a textual er‐ ror message, which the caller should later free(3).
PMAPI(3), pmUnitsStr(3), pmConvScale(3), and pmLookupDesc(3).
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