ftoa (x, str, prec, format) float x; char *str; { /* converts a floating point number to an ascii string */ /* x is stored into str, which should be at least 30 chars long */ int ie, i, k, ndig, fstyle; double y; if (nargs() != 7) IEHzap("ftoa "); ndig = ( prec<=0) ? 7 : (prec > 22 ? 23 : prec+1); if (format == 'f' || format == 'F') fstyle = 1; else fstyle = 0; /* print in e format unless last arg is 'f' */ ie = 0; /* if x negative, write minus and reverse */ if ( x < 0) { *str++ = '-'; x = -x; } /* put x in range 1 <= x < 10 */ if (x > 0.0) while (x < 1.0) { x =* 10.0; ie--; } while (x >= 10.0) { x = x/10.0; ie++; } /* in f format, number of digits is related to size */ if (fstyle) ndig =+ ie; /* round. x is between 1 and 10 and ndig will be printed to right of decimal point so rounding is ... */ for (y = i = 1; i < ndig; i++) y = y/10.; x =+ y/2.; if (x >= 10.0) {x = 1.0; ie++;} /* repair rounding disasters */ /* now loop. put out a digit (obtain by multiplying by 10, truncating, subtracting) until enough digits out */ /* if fstyle, and leading zeros, they go out special */ if (fstyle && ie<0) { *str++ = '0'; *str++ = '.'; if (ndig < 0) ie = ie-ndig; /* limit zeros if underflow */ for (i = -1; i > ie; i--) *str++ = '0'; } for (i=0; i < ndig; i++) { k = x; *str++ = k + '0'; if (i == (fstyle ? ie : 0)) /* where is decimal point */ *str++ = '.'; x =- (y=k); x =* 10.0; } /* now, in estyle, put out exponent if not zero */ if (!fstyle && ie != 0) { *str++ = 'E'; if (ie < 0) { ie = -ie; *str++ = '-'; } for (k=100; k > ie; k =/10); for (; k > 0; k =/10) { *str++ = ie/k + '0'; ie = ie%k; } } *str = '\0'; return; }