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