160 lines
2.9 KiB
C
160 lines
2.9 KiB
C
/*
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** take a string that is a number in a certain and convert it in another base
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** return the new string
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*/
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#include <stdio.h> // for printf
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#include <stdlib.h> // for atoi
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char *ft_convertbase(char *nbr, char *base_from, char *base_to);
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int main(int ac, char **av)
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{
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if (ac != 4)
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printf("usage:\nchar *nbr, char *base_from, char *base_to\ntry the max long unsigned int : 9223372036854775807");
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else
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printf("[%s]\n",ft_convertbase(av[1], av[2], av[3]));
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return (0);
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}
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#include "libft.h"
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/*
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** check :
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** -if the base has no characters that appear more than one time
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** -if the signes '-' and '+' are not part of the set
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** -if there are no invisible characters (inferior to 32 or equal to 127)
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*/
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int
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is_valid_base(char *base)
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{
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int i;
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int j;
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i = 0;
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while (base[i])
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{
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j = i + 1;
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while (base[j])
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if (base[i] == base[j++])
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return (0);
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if (base[i] == '-' || base[i] == '+' || base[i] < 33 || base[i] == 127)
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return (0);
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i++;
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}
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if (i >= 2)
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return (1);
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return (0);
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}
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/*
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** check :
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** -if base is valid
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** -if nbr contain characters
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** -if nbr is made of elements of base only
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*/
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int
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is_valid_nbr(char *nbr, char *base)
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{
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int i;
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int j;
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i = 0;
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if (!is_valid_base(base))
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return (0);
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while (nbr[i])
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{
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j = 0;
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while (base[j] && nbr[i] != base[j])
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j++;
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if (base[j] == '\0')
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return (0);
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i++;
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}
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if (i == 0)
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return (0);
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return (1);
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}
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/*
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** -transform a nbr written as a string into a decimal nbr
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** -it's an unsigned nbr because the negativity is managed elsewhere
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** -if the number is bigger than the max unsigned long int it's false
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*/
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unsigned long int
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base_to_decimal(char *nbr, char *base)
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{
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unsigned long int decimal;
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int i;
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int j;
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int length;
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decimal = 0;
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i = 0;
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length = 0;
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while (base[length])
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length++;
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while (nbr[i])
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{
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j = 0;
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while (nbr[i] != base[j] && base[j])
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j++;
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if ((18446744073709551615U - j) / length > decimal)
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return (0);
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decimal = (decimal * length) + j;
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i++;
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}
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return (decimal);
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}
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char
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*decimal_to_base(unsigned long int decimal, char *base, int malloc_size)
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{
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int base_size;
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int neg;
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char *result;
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unsigned long int nb;
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neg = malloc_size;
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base_size = 0;
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while (base[base_size])
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base_size++;
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nb = decimal;
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while (nb /= base_size)
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malloc_size++;
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result = (char *)malloc(sizeof(char) * (malloc_size + 2));
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result[malloc_size + 1] = '\0';
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if (neg)
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result[0] = '-';
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while (malloc_size >= 0)
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{
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result[malloc_size--] = base[decimal % base_size];
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decimal /= base_size;
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}
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return (result);
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}
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char
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*ft_convertbase(char *nbr, char *base_from, char *base_to)
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{
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int length;
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unsigned long int decimal;
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length = 0;
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if (nbr[0] == '-')
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{
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nbr++;
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length = 1;
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}
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if (!is_valid_nbr(nbr, base_from) || !is_valid_base(base_to))
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return (NULL);
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if ((decimal = base_to_decimal(nbr, base_from)) == 0)
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return (NULL);
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return (decimal_to_base(decimal, base_to, length));
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}
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