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3.8.1 The numeric type
The numeric type offers to do calculations with arbitrary precision. See
Volume 1: Numeric Types for the equivalent type in the
PostgreSQL server. Because of the arbitrary precision this
variable needs to be able to expand and shrink dynamically. That's why you
can only create variables on the heap by means of the
PGTYPESnumeric_new
and PGTYPESnumeric_free
functions. The decimal type, which is similar but limited in the precision,
can be created on the stack as well as on the heap.
The following functions can be used to work with the numeric type:
PGTYPESnumeric_new

Request a pointer to a newly allocated numeric variable.
numeric *PGTYPESnumeric_new(void);
PGTYPESnumeric_free

Free a numeric type, release all of its memory.
void PGTYPESnumeric_free(numeric *var);
PGTYPESnumeric_from_asc

Parse a numeric type from its string notation.
numeric *PGTYPESnumeric_from_asc(char *str, char **endptr);
Valid formats are for example:2
,.794
,+3.44
,592.49E07
or32.84e4
. If the value could be parsed successfully, a valid pointer is returned, else the NULL pointer. At the moment ecpg always parses the complete string and so it currently does not support to store the address of the first invalid character in*endptr
. You can safely setendptr
to NULL. PGTYPESnumeric_to_asc

Returns a pointer to a string allocated by
malloc
that contains the string representation of the numeric typenum
.char *PGTYPESnumeric_to_asc(numeric *num, int dscale);
The numeric value will be printed withdscale
decimal digits, with rounding applied if necessary. PGTYPESnumeric_add

Add two numeric variables into a third one.
int PGTYPESnumeric_add(numeric *var1, numeric *var2, numeric *result);
The function adds the variablesvar1
andvar2
into the result variableresult
. The function returns 0 on success and 1 in case of error. PGTYPESnumeric_sub

Subtract two numeric variables and return the result in a third one.
int PGTYPESnumeric_sub(numeric *var1, numeric *var2, numeric *result);
The function subtracts the variablevar2
from the variablevar1
. The result of the operation is stored in the variableresult
. The function returns 0 on success and 1 in case of error. PGTYPESnumeric_mul

Multiply two numeric variables and return the result in a third one.
int PGTYPESnumeric_mul(numeric *var1, numeric *var2, numeric *result);
The function multiplies the variablesvar1
andvar2
. The result of the operation is stored in the variableresult
. The function returns 0 on success and 1 in case of error. PGTYPESnumeric_div

Divide two numeric variables and return the result in a third one.
int PGTYPESnumeric_div(numeric *var1, numeric *var2, numeric *result);
The function divides the variablesvar1
byvar2
. The result of the operation is stored in the variableresult
. The function returns 0 on success and 1 in case of error. PGTYPESnumeric_cmp

Compare two numeric variables.
int PGTYPESnumeric_cmp(numeric *var1, numeric *var2)
This function compares two numeric variables. In case of error,INT_MAX
is returned. On success, the function returns one of three possible results:
1, if
var1
is bigger thanvar2

1, if
var1
is smaller thanvar2

0, if
var1
andvar2
are equal

1, if
PGTYPESnumeric_from_int

Convert an int variable to a numeric variable.
int PGTYPESnumeric_from_int(signed int int_val, numeric *var);
This function accepts a variable of type signed int and stores it in the numeric variablevar
. Upon success, 0 is returned and 1 in case of a failure. PGTYPESnumeric_from_long

Convert a long int variable to a numeric variable.
int PGTYPESnumeric_from_long(signed long int long_val, numeric *var);
This function accepts a variable of type signed long int and stores it in the numeric variablevar
. Upon success, 0 is returned and 1 in case of a failure. PGTYPESnumeric_copy

Copy over one numeric variable into another one.
int PGTYPESnumeric_copy(numeric *src, numeric *dst);
This function copies over the value of the variable thatsrc
points to into the variable thatdst
points to. It returns 0 on success and 1 if an error occurs. PGTYPESnumeric_from_double

Convert a variable of type double to a numeric.
int PGTYPESnumeric_from_double(double d, numeric *dst);
This function accepts a variable of type double and stores the result in the variable thatdst
points to. It returns 0 on success and 1 if an error occurs. PGTYPESnumeric_to_double

Convert a variable of type numeric to double.
int PGTYPESnumeric_to_double(numeric *nv, double *dp)
The function converts the numeric value from the variable thatnv
points to into the double variable thatdp
points to. It returns 0 on success and 1 if an error occurs, including overflow. On overflow, the global variableerrno
will be set toPGTYPES_NUM_OVERFLOW
additionally. PGTYPESnumeric_to_int

Convert a variable of type numeric to int.
int PGTYPESnumeric_to_int(numeric *nv, int *ip);
The function converts the numeric value from the variable thatnv
points to into the integer variable thatip
points to. It returns 0 on success and 1 if an error occurs, including overflow. On overflow, the global variableerrno
will be set toPGTYPES_NUM_OVERFLOW
additionally. PGTYPESnumeric_to_long

Convert a variable of type numeric to long.
int PGTYPESnumeric_to_long(numeric *nv, long *lp);
The function converts the numeric value from the variable thatnv
points to into the long integer variable thatlp
points to. It returns 0 on success and 1 if an error occurs, including overflow. On overflow, the global variableerrno
will be set toPGTYPES_NUM_OVERFLOW
additionally. PGTYPESnumeric_to_decimal

Convert a variable of type numeric to decimal.
int PGTYPESnumeric_to_decimal(numeric *src, decimal *dst);
The function converts the numeric value from the variable thatsrc
points to into the decimal variable thatdst
points to. It returns 0 on success and 1 if an error occurs, including overflow. On overflow, the global variableerrno
will be set toPGTYPES_NUM_OVERFLOW
additionally. PGTYPESnumeric_from_decimal

Convert a variable of type decimal to numeric.
int PGTYPESnumeric_from_decimal(decimal *src, numeric *dst);
The function converts the decimal value from the variable thatsrc
points to into the numeric variable thatdst
points to. It returns 0 on success and 1 if an error occurs. Since the decimal type is implemented as a limited version of the numeric type, overflow can not occur with this conversion.
ISBN 0954612035  PostgreSQL Reference Manual  Volume 2  Programming Guide  See the print edition 