Eina_Convert_Group(3)

NAME
Eina_Convert_Group - Convert

 - These functions allow you to convert integer or real numbers to string or conversely.

SYNOPSIS

  Functions
EINA_API int eina_convert_itoa (int n, char *s)
Converts an integer number to a string in decimal base.
EINA_API int eina_convert_xtoa (unsigned int n, char *s)
Converts an integer number to a string in hexadecimal base.
EINA_API int eina_convert_dtoa (double d, char *des)
Converts a double to a string.
EINA_API Eina_Bool eina_convert_atod (const char *src, int length, long long *m, long *e)
Converts a string to a double.
EINA_API int eina_convert_fptoa (Eina_F32p32 fp, char *des)
Converts a 32.32 fixed point number to a string.
EINA_API Eina_Bool eina_convert_atofp (const char *src, int length, Eina_F32p32 *fp)
Converts a string to a 32.32 fixed point number.
EINA_API double eina_convert_strtod_c (const char *nptr, char **endptr)
Converts a string to a floating point number.

  Variables
EINA_API Eina_Error EINA_ERROR_CONVERT_P_NOT_FOUND
Not used, perhaps a placeholder? Defined as 0 in eina_convert.c.
EINA_API Eina_Error EINA_ERROR_CONVERT_0X_NOT_FOUND
Not used, perhaps a placeholder? Defined as 0 in eina_convert.c.
EINA_API Eina_Error EINA_ERROR_CONVERT_OUTRUN_STRING_LENGTH
Not used, perhaps a placeholder? Defined as 0 in eina_convert.c.

Detailed Description

These functions allow you to convert integer or real numbers to string or conversely. To use these functions, you have to call eina_init() first, and eina_shutdown() when eina is not used anymore.

Conversion from integer to string

To convert an integer to a string in the decimal base, eina_convert_itoa() should be used. If the hexadecimal base is wanted, eina_convert_xtoa() should be used. They all need a buffer sufficiently large to store all the cyphers.

Here is an example of use:

#include <stdlib.h>
#include <stdio.h>
#include <Eina.h>
int main(void)
{
   char tmp[128];
   if (!eina_init())
   {
       printf ("Error during the initialization of eina.);
       return EXIT_FAILURE;
   }
   eina_convert_itoa(45, tmp);
   printf("value: %s, tmp);
   eina_convert_xtoa(0xA1, tmp);
   printf("value: %s, tmp);
   eina_shutdown();
   return EXIT_SUCCESS;
}

Compile this code with the following command:

gcc -Wall -o test_eina_convert test_eina.c `pkg-config --cflags --libs eina`

Note
    The alphabetical cyphers are in lower case.

Conversion double / string

To convert a double to a string, eina_convert_dtoa() should be used. Like with the integer functions, a buffer must be used. The resulting string has the following format (which is the result obtained with snprintf() and the %a modifier):

[-]0xh.hhhhhp[+-]e

To convert a string to a double, eina_convert_atod() should be used. The format of the string must be as above. Then, the double has the following mantissas and exponent:

mantissa  : [-]hhhhhh
exponent : 2^([+-]e - 4 * n)

with n being number of cyphers after the point in the string format. To obtain the double number from the mantissas and exponent, use ldexp().

Here is an example of use:

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <Eina.h>
int main(void)
{
   char      tmp[128];
   long long int m = 0;
   long int  e = 0;
   double    r;
   if (!eina_init())
   {
       printf ("Error during the initialization of eina.);
       return EXIT_FAILURE;
   }
   printf("initial value : 40.56);
   eina_convert_dtoa(40.56, tmp);
   printf("result dtoa   : %s, tmp);
   eina_convert_atod(tmp, 128, &m, &e);
   r = ldexp((double)m, e);
   printf("result atod   : %f, r);
   eina_shutdown();
   return EXIT_SUCCESS;
}

Compile this code with the following command:

gcc -Wall -o test_eina_convert test_eina.c `pkg-config --cflags --libs eina` -lm

Function Documentation

  EINA_API int eina_convert_itoa (int n, char * s)

Converts an integer number to a string in decimal base.

Parameters
    n The integer to convert.
    s The buffer to store the converted integer.

Returns
    The length of the string, including the null terminated character.

This function converts n to a null terminated string. The converted string is in decimal base. As no check is done, s must be a buffer that is sufficiently large to store the integer.

The returned value is the length of the string, including the null terminated character.

References EINA_SAFETY_ON_NULL_RETURN_VAL.

Referenced by eina_convert_dtoa(), eina_convert_fptoa(), and eina_xattr_int_set().

  EINA_API int eina_convert_xtoa (unsigned int n, char * s)

Converts an integer number to a string in hexadecimal base.

Parameters
    n The integer to convert.
    s The buffer to store the converted integer.

Returns
    The length of the string, including the null terminated character.

This function converts n to a null terminated string. The converted string is in hexadecimal base and the alphabetical cyphers are in lower case. As no check is done, s must be a buffer that is sufficiently large to store the integer.

The returned value is the length of the string, including the nul terminated character.

References EINA_SAFETY_ON_NULL_RETURN_VAL.

  EINA_API int eina_convert_dtoa (double d, char * des)

Converts a double to a string.

Parameters
    d The double to convert.
    des The destination buffer to store the converted double.

Returns
    EINA_TRUE on success, EINA_FALSE otherwise.

This function converts the double d to a string. The string is stored in the buffer pointed by des and must be sufficiently large to contain the converted double. The returned string is null terminated and has the following format:

[-]0xh.hhhhhp[+-]e

where the h are the hexadecimal cyphers of the mantissas and e the exponent (a decimal number).

The returned value is the length of the string, including the null character.

References eina_convert_itoa(), EINA_SAFETY_ON_FALSE_RETURN_VAL, and EINA_SAFETY_ON_NULL_RETURN_VAL.

Referenced by eina_xattr_double_set().

  EINA_API Eina_Bool eina_convert_atod (const char * src, int length, long long * m, long * e)

Converts a string to a double.

Parameters
    src The string to convert.
    length The length of the string.
    m The mantissa.
    e The exponent.

Returns
    EINA_TRUE on success, EINA_FALSE otherwise.

This function converts the string s of length length that represent a double in hexadecimal base to a double. It is used to replace the use of snprintf() with the %a modifier, which is missing on some platform (like Windows (tm) or OpenBSD).

The string must have the following format:

[-]0xh.hhhhhp[+-]e

where the h are the hexadecimal cyphers of the mantissas and e the exponent (a decimal number). If n is the number of cyphers after the point, the returned mantissas and exponents are:

mantissa  : [-]hhhhhh
exponent : 2^([+-]e - 4 * n)

The mantissas and exponent are stored in the buffers pointed respectively by m and e.

If the string is invalid EINA_FALSE is returned, otherwise EINA_TRUE is returned.

References DBG, EINA_FALSE, EINA_SAFETY_ON_NULL_RETURN_VAL, and EINA_TRUE.

Referenced by eina_convert_atofp(), and eina_xattr_double_get().

  EINA_API int eina_convert_fptoa (Eina_F32p32 fp, char * des)

Converts a 32.32 fixed point number to a string.

Parameters
    fp The fixed point number to convert.
    des The destination buffer to store the converted fixed point number.

Returns
    EINA_TRUE on success, EINA_FALSE otherwise.

This function converts the 32.32 fixed point number fp to a string. The string is stored in the buffer pointed by des and must be sufficiently large to contain the converted fixed point number. The returned string is terminated and has the following format:

[-]0xh.hhhhhp[+-]e

where the h are the hexadecimal cyphers of the mantissas and e the exponent (a decimal number).

The returned value is the length of the string, including the null character.

Note
    The code is the same than eina_convert_dtoa() except that it implements the frexp() function for fixed point numbers and does some optimization.

References eina_convert_itoa(), EINA_FALSE, and EINA_SAFETY_ON_NULL_RETURN_VAL.

  EINA_API Eina_Bool eina_convert_atofp (const char * src, int length, Eina_F32p32 * fp)

Converts a string to a 32.32 fixed point number.

Parameters
    src The string to convert.
    length The length of the string.
    fp The fixed point number.

Returns
    EINA_TRUE on success, EINA_FALSE otherwise.

This function converts the string src of length length that represent a double in hexadecimal base to a 32.32 fixed point number stored in fp. The function always tries to convert the string with eina_convert_atod().

The string must have the following format:

[-]0xh.hhhhhp[+-]e

where the h's are the hexadecimal cyphers of the mantissas and e the exponent (a decimal number). If n is the number of cyphers after the point, the returned mantissas and exponents are:

mantissa  : [-]hhhhhh
exponent : 2^([+-]e - 4 * n)

The mantissas and exponent are stored in the buffers pointed respectively by m and e.

If the string is invalid, EINA_FALSE is returned, otherwise fp is computed and EINA_TRUE is returned.

Note
    The code uses eina_convert_atod() and do the correct bit shift to compute the fixed point number.

References eina_convert_atod(), EINA_FALSE, and EINA_TRUE.

  EINA_API double eina_convert_strtod_c (const char * nptr, char ** endptr)

Converts a string to a floating point number.

Parameters
    nptr a string to convert. It shouldn't be NULL.
    endptr If endptr is not NULL, a pointer to the character after the last character used in the conversion is stored in the location referenced by endptr. If nptr is NULL, this will also be set to NULL.

Returns
    a double type floating point number.

This function returns converted floating point number with locale-independency. Actually, it use 'C' locale for strtod_l function internally. If you need strtod without locale-dependency, this function can replace strtod. For more information, please refer documents of strtod, strtod_l.

References eina_dbl_exact(), and EINA_SAFETY_ON_NULL_RETURN_VAL.

Author

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