31 lines
429 B
C
31 lines
429 B
C
#include <errno.h>
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#include <float.h>
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#include <math.h>
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static long tab[] =
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{
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1L, 10L, 100L, 1000L, 10000L,
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100000L, 1000000L, 10000000L
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};
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double
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pow10(int n)
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{
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int m;
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if(n > DBL_MAX_10_EXP){
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errno = ERANGE;
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return HUGE_VAL;
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}
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if(n < DBL_MIN_10_EXP){
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errno = ERANGE;
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return 0.0;
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}
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if(n < 0)
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return 1/pow10(-n);
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if(n < sizeof(tab)/sizeof(tab[0]))
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return tab[n];
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m = n/2;
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return pow10(m) * pow10(n-m);
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}
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