mirror of https://github.com/TheAlgorithms/C
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
/**
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* \file
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* \brief Recoding the original atoi function in stdlib.h
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* \author [Mohammed YMIK](https://github.com/medymik)W
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* The function convert a string passed to an integer
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*/
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/**
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* the function take a string and return an integer
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* \param[out] str pointer to a char address
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*/
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int c_atoi(const char *str)
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{
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int i;
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int sign;
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long value;
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long prev;
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i = 0;
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sign = 1;
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value = 0;
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/* skipping the spaces */
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while (((str[i] <= 13 && str[i] >= 9) || str[i] == 32) && str[i] != '\0')
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i++;
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/* store the sign if it is negative sign */
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if (str[i] == '-')
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{
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sign = -1;
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i++;
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}
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else if (str[i] == '+')
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{
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sign = 1;
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i++;
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}
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/* converting char by char to a numeric value */
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while (str[i] >= 48 && str[i] <= 57 && str[i] != '\0')
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{
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prev = value;
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value = value * 10 + sign * (str[i] - '0');
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/* managing the overflow */
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if (sign == 1 && prev > value)
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return (-1);
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else if (sign == -1 && prev < value)
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return (0);
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i++;
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}
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return (value);
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}
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/**
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* test the function implementation
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*/
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void test_c_atoi()
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{
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printf("<<<< TEST FUNCTION >>>>\n");
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assert(c_atoi("123") == atoi("123"));
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assert(c_atoi("-123") == atoi("-123"));
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assert(c_atoi("") == atoi(""));
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assert(c_atoi("-h23") == atoi("-h23"));
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assert(c_atoi(" 23") == atoi(" 23"));
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assert(c_atoi("999999999") == atoi("999999999"));
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printf("<<<< TEST DONE >>>>\n");
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}
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/**
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* the main function take one argument of type char*
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* example : ./program 123
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*/
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int main(int argc, char **argv)
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{
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test_c_atoi();
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if (argc == 2)
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{
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printf("Your number + 5 is %d\n", c_atoi(argv[1]) + 5);
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return (0);
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}
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printf("wrong number of parmeters\n");
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return (1);
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}
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