c_atoi_str_to_integer.c File Reference

Recoding the original atoi function in stdlib.h. More...

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

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Functions
int	c_atoi (const char *str)
	the function take a string and return an integer
void	test_c_atoi ()
	test the function implementation
int	main (int argc, char **argv)
	the main function take one argument of type char* example : .

Detailed Description

Recoding the original atoi function in stdlib.h.

Author

Mohammed YMIKW The function convert a string passed to an integer

Function Documentation

c_atoi()

int c_atoi

(

const char *

str

)

the function take a string and return an integer

Parameters

[out]

str

pointer to a char address

{
    int i;
    int sign;
    long value;
    long prev;
 
    i = 0;
    sign = 1;
    value = 0;
 
    /* skipping the spaces */
    while (((str[i] <= 13 && str[i] >= 9) || str[i] == 32) && str[i] != '\0')
        i++;
 
    /* store the sign if it is negative sign */
    if (str[i] == '-')
    {
        sign = -1;
    i++;
    }
    else if (str[i] == '+')
    {
        sign = 1;
    i++;
    }
 
    /* converting char by char to a numeric value */
    while (str[i] >= 48 && str[i] <= 57 && str[i] != '\0')
    {
        prev = value;
        value = value * 10 + sign * (str[i] - '0');
 
        /* managing the overflow */
        if (sign == 1 && prev > value)
            return (-1);
        else if (sign == -1 && prev < value)
            return (0);
        i++;
    }
    return (value);
}

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main()

int main	(	int	argc,
		char **	argv
	)

the main function take one argument of type char* example : .

/program 123

{
    test_c_atoi();
 
    if (argc == 2)
    {
        printf("Your number + 5 is %d\n", c_atoi(argv[1]) + 5);
        return (0);
    }
    printf("wrong number of parmeters\n");
    return (1);
}

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test_c_atoi()

void test_c_atoi

(

)

test the function implementation

{
    printf("<<<< TEST FUNCTION >>>>\n");
    assert(c_atoi("123") == atoi("123"));
    assert(c_atoi("-123") == atoi("-123"));
    assert(c_atoi("") == atoi(""));
    assert(c_atoi("-h23") == atoi("-h23"));
    assert(c_atoi("         23") == atoi("         23"));
    assert(c_atoi("999999999") == atoi("999999999"));
    printf("<<<< TEST DONE >>>>\n");
}

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