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Synopsis

#include <floatingpoint.h>

char *econvert(double value, int ndigit, int *decpt, int *sign, char *buf);

char *fconvert(double value, int ndigit, int *decpt, int *sign, char *buf);

char *gconvert(double value, int ndigit, int trailing, char *buf);

char *seconvert(single *value, int ndigit, int *decpt, int *sign, char *buf);

char *sfconvert(single *value, int ndigit, int *decpt, int *sign, char *buf);

char *sgconvert(single *value, int ndigit, int trailing, char *buf );

char *qeconvert(quadruple *value, int ndigit, int *decpt, int *sign, char *buf);

char *qfconvert(quadruple *value, int ndigit, int *decpt, int *sign, char *buf);

char *qgconvert(quadruple *value, int ndigit, int trailing, char *buf );

char *ecvt(double value, int ndigit, int *decpt, int *sign);

char *fcvt(double value, int ndigit, int *decpt, int *sign);

char *gcvt(double value, int ndigit, char *buf);

MT-Level

MT-Safe

Description

econvert() converts the value to a NULL -terminated string of ndigit ASCII digits in buf and returns a pointer to buf. buf should contain at least ndigit+1 characters. The position of the decimal point relative to the beginning of the string is stored indirectly through decpt. Thus buf == "314" and *decpt == 1 corresponds to the numerical value 3.14, while buf == "314" and *decpt == -1 corresponds to the numerical value .0314. If the sign of the result is negative, the word pointed to by sign is nonzero; otherwise it is zero. The least significant digit is rounded.

fconvert works much like econvert", except that the correct digit has been rounded as if for sprintf(%w.nf) output with n=ndigit digits to the right of the decimal point. ndigit can be negative to indicate rounding to the left of the decimal point. The return value is a pointer to buf. buf should contain at least 310+max(0,ndigit) characters to accomodate any double-precision value.

gconvert() converts the value to a NULL -terminated ASCII string in buf and returns a pointer to buf. It produces ndigit significant digits in fixed-decimal format, like sprintf(%w.nf), if possible, and otherwise in floating-decimal format, like sprintf(%w.ne); in either case buf is ready for printing, with sign and exponent. The result corresponds to that obtained by

    (void) sprintf(buf,‘‘%w.ng’’,value) ;

seconvert, sfconvert, and sgconvert() are single-precision versions of these functions, and are more efficient than the corresponding double-precision versions. A pointer rather than the value itself is passed to avoid C’s usual conversion of single-precision arguments to double.

qeconvert, qfconvert, and qgconvert() are quadruple-precision versions of these functions. qfconvert() can overflow the decimal_record field ds if value is too large. In that case, buf[0] is set to zero.

ecvt() and fcvt() are obsolete versions of econvert() and fconvert() that create a string in a static data area, overwritten by each call, and return values that point to that static data. These functions are therefore not reentrant.

gcvt() is an obsolete version of gconvert() that always suppresses trailing zeros and point.

IEEE Infinities and NaNs are treated similarly by these functions. ‘‘NaN’’ is returned for NaN, and ‘‘Inf’’ or ‘‘Infinity’’ for Infinity. The longer form is produced when ndigit >= 8.

See Also

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