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PostgreSQL Reference Manual - Volume 2 - Programming Guide
by The PostgreSQL Global Development Group
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3.9.2 Additional functions

decadd
Add two decimal type values.
int decadd(decimal *arg1, decimal *arg2, decimal *sum);
The function receives a pointer to the first operand of type decimal (arg1), a pointer to the second operand of type decimal (arg2) and a pointer to a value of type decimal that will contain the sum (sum). On success, the function returns 0. ECPG_INFORMIX_NUM_OVERFLOW is returned in case of overflow and ECPG_INFORMIX_NUM_UNDERFLOW in case of underflow. -1 is returned for other failures and errno is set to the respective errno number of the pgtypeslib.
deccmp
Compare two variables of type decimal.
int deccmp(decimal *arg1, decimal *arg2);
The function receives a pointer to the first decimal value (arg1), a pointer to the second decimal value (arg2) and returns an integer value that indicates which is the bigger value.
  • 1, if the value that arg1 points to is bigger than the value that var2 points to
  • -1, if the value that arg1 points to is smaller than the value that arg2 points to
  • 0, if the value that arg1 points to and the value that arg2 points to are equal
deccopy
Copy a decimal value.
void deccopy(decimal *src, decimal *target);
The function receives a pointer to the decimal value that should be copied as the first argument (src) and a pointer to the target structure of type decimal (target) as the second argument.
deccvasc
Convert a value from its ASCII representation into a decimal type.
int deccvasc(char *cp, int len, decimal *np);
The function receives a pointer to string that contains the string representation of the number to be converted (cp) as well as its length len. np is a pointer to the decimal value that saves the result of the operation. Valid formats are for example: -2, .794, +3.44, 592.49E07 or -32.84e-4. The function returns 0 on success. If overflow or underflow occurred, ECPG_INFORMIX_NUM_OVERFLOW or ECPG_INFORMIX_NUM_UNDERFLOW is returned. If the ASCII representation could not be parsed, ECPG_INFORMIX_BAD_NUMERIC is returned or ECPG_INFORMIX_BAD_EXPONENT if this problem occurred while parsing the exponent.
deccvdbl
Convert a value of type double to a value of type decimal.
int deccvdbl(double dbl, decimal *np);
The function receives the variable of type double that should be converted as its first argument (dbl). As the second argument (np), the function receives a pointer to the decimal variable that should hold the result of the operation. The function returns 0 on success and a negative value if the conversion failed.
deccvint
Convert a value of type int to a value of type decimal.
int deccvint(int in, decimal *np);
The function receives the variable of type int that should be converted as its first argument (in). As the second argument (np), the function receives a pointer to the decimal variable that should hold the result of the operation. The function returns 0 on success and a negative value if the conversion failed.
deccvlong
Convert a value of type long to a value of type decimal.
int deccvlong(long lng, decimal *np);
The function receives the variable of type long that should be converted as its first argument (lng). As the second argument (np), the function receives a pointer to the decimal variable that should hold the result of the operation. The function returns 0 on success and a negative value if the conversion failed.
decdiv
Divide two variables of type decimal.
int decdiv(decimal *n1, decimal *n2, decimal *result);
The function receives pointers to the variables that are the first (n1) and the second (n2) operands and calculates n1/n2. result is a pointer to the variable that should hold the result of the operation. On success, 0 is returned and a negative value if the division fails. If overflow or underflow occurred, the function returns ECPG_INFORMIX_NUM_OVERFLOW or ECPG_INFORMIX_NUM_UNDERFLOW respectively. If an attempt to divide by zero is observed, the function returns ECPG_INFORMIX_DIVIDE_ZERO.
decmul
Multiply two decimal values.
int decmul(decimal *n1, decimal *n2, decimal *result);
The function receives pointers to the variables that are the first (n1) and the second (n2) operands and calculates n1*n2. result is a pointer to the variable that should hold the result of the operation. On success, 0 is returned and a negative value if the multiplication fails. If overflow or underflow occurred, the function returns ECPG_INFORMIX_NUM_OVERFLOW or ECPG_INFORMIX_NUM_UNDERFLOW respectively.
decsub
Subtract one decimal value from another.
int decsub(decimal *n1, decimal *n2, decimal *result);
The function receives pointers to the variables that are the first (n1) and the second (n2) operands and calculates n1-n2. result is a pointer to the variable that should hold the result of the operation. On success, 0 is returned and a negative value if the subtraction fails. If overflow or underflow occurred, the function returns ECPG_INFORMIX_NUM_OVERFLOW or ECPG_INFORMIX_NUM_UNDERFLOW respectively.
dectoasc
Convert a variable of type decimal to its ASCII representation in a C char* string.
int dectoasc(decimal *np, char *cp, int len, int right)
The function receives a pointer to a variable of type decimal (np) that it converts to its textual representation. cp is the buffer that should hold the result of the operation. The parameter right specifies, how many digits right of the decimal point should be included in the output. The result will be rounded to this number of decimal digits. Setting right to -1 indicates that all available decimal digits should be included in the output. If the length of the output buffer, which is indicated by len is not sufficient to hold the textual representation including the trailing NUL character, only a single * character is stored in the result and -1 is returned. The function returns either -1 if the buffer cp was too small or ECPG_INFORMIX_OUT_OF_MEMORY if memory was exhausted.
dectodbl
Convert a variable of type decimal to a double.
int dectodbl(decimal *np, double *dblp);
The function receives a pointer to the decimal value to convert (np) and a pointer to the double variable that should hold the result of the operation (dblp). On success, 0 is returned and a negative value if the conversion failed.
dectoint
Convert a variable to type decimal to an integer.
int dectoint(decimal *np, int *ip);
The function receives a pointer to the decimal value to convert (np) and a pointer to the integer variable that should hold the result of the operation (ip). On success, 0 is returned and a negative value if the conversion failed. If an overflow occurred, ECPG_INFORMIX_NUM_OVERFLOW is returned. Note that the ecpg implementation differs from the Informix implementation. Informix limits an integer to the range from -32767 to 32767, while the limits in the ecpg implementation depend on the architecture (-INT_MAX .. INT_MAX).
dectolong
Convert a variable to type decimal to a long integer.
int dectolong(decimal *np, long *lngp);
The function receives a pointer to the decimal value to convert (np) and a pointer to the long variable that should hold the result of the operation (lngp). On success, 0 is returned and a negative value if the conversion failed. If an overflow occurred, ECPG_INFORMIX_NUM_OVERFLOW is returned. Note that the ecpg implementation differs from the Informix implementation. Informix limits a long integer to the range from -2,147,483,647 to 2,147,483,647, while the limits in the ecpg implementation depend on the architecture (-LONG_MAX .. LONG_MAX).
rdatestr
Converts a date to a C char* string.
int rdatestr(date d, char *str);
The function receives two arguments, the first one is the date to convert (d and the second one is a pointer to the target string. The output format is always yyyy-mm-dd, so you need to allocate at least 11 bytes (including the NUL-terminator) for the string. The function returns 0 on success and a negative value in case of error. Note that ecpg's implementation differs from the Informix implementation. In Informix the format can be influenced by setting environment variables. In ecpg however, you cannot change the output format.
rstrdate
Parse the textual representation of a date.
int rstrdate(char *str, date *d);
The function receives the textual representation of the date to convert (str) and a pointer to a variable of type date (d). This function does not allow you to specify a format mask. It uses the default format mask of Informix which is mm/dd/yyyy. Internally, this function is implemented by means of rdefmtdate. Therefore, rstrdate is not faster and if you have the choice you should opt for rdefmtdate which allows you to specify the format mask explicitly. The function returns the same values as rdefmtdate.
rtoday
Get the current date.
void rtoday(date *d);
The function receives a pointer to a date variable (d) that it sets to the current date. Internally this function uses the section 3.8.2 The date type function.
rjulmdy
Extract the values for the day, the month and the year from a variable of type date.
int rjulmdy(date d, short mdy[3]);
The function receives the date d and a pointer to an array of 3 short integer values mdy. The variable name indicates the sequential order: mdy[0] will be set to contain the number of the month, mdy[1] will be set to the value of the day and mdy[2] will contain the year. The function always returns 0 at the moment. Internally the function uses the section 3.8.2 The date type function.
rdefmtdate
Use a format mask to convert a character string to a value of type date.
int rdefmtdate(date *d, char *fmt, char *str);
The function receives a pointer to the date value that should hold the result of the operation (d), the format mask to use for parsing the date (fmt) and the C char* string containing the textual representation of the date (str). The textual representation is expected to match the format mask. However you do not need to have a 1:1 mapping of the string to the format mask. The function only analyzes the sequential order and looks for the literals yy or yyyy that indicate the position of the year, mm to indicate the position of the month and dd to indicate the position of the day. The function returns the following values:
  • 0 - The function terminated successfully.
  • ECPG_INFORMIX_ENOSHORTDATE - The date does not contain delimiters between day, month and year. In this case the input string must be exactly 6 or 8 bytes long but isn't.
  • ECPG_INFORMIX_ENOTDMY - The format string did not correctly indicate the sequential order of year, month and day.
  • ECPG_INFORMIX_BAD_DAY - The input string does not contain a valid day.
  • ECPG_INFORMIX_BAD_MONTH - The input string does not contain a valid month.
  • ECPG_INFORMIX_BAD_YEAR - The input string does not contain a valid year.
Internally this function is implemented to use the section 3.8.2 The date type function. See the reference there for a table of example input.
rfmtdate
Convert a variable of type date to its textual representation using a format mask.
int rfmtdate(date d, char *fmt, char *str);
The function receives the date to convert (d), the format mask (fmt) and the string that will hold the textual representation of the date (str). On success, 0 is returned and a negative value if an error occurred. Internally this function uses the section 3.8.2 The date type function, see the reference there for examples.
rmdyjul
Create a date value from an array of 3 short integers that specify the day, the month and the year of the date.
int rmdyjul(short mdy[3], date *d);
The function receives the array of the 3 short integers (mdy) and a pointer to a variable of type date that should hold the result of the operation. Currently the function returns always 0. Internally the function is implemented to use the function section 3.8.2 The date type.
rdayofweek
Return a number representing the day of the week for a date value.
int rdayofweek(date d);
The function receives the date variable d as its only argument and returns an integer that indicates the day of the week for this date.
  • 0 - Sunday
  • 1 - Monday
  • 2 - Tuesday
  • 3 - Wednesday
  • 4 - Thursday
  • 5 - Friday
  • 6 - Saturday
Internally the function is implemented to use the function section 3.8.2 The date type.
dtcurrent
Retrieve the current timestamp.
void dtcurrent(timestamp *ts);
The function retrieves the current timestamp and saves it into the timestamp variable that ts points to.
dtcvasc
Parses a timestamp from its textual representation in ANSI standard into a timestamp variable.
int dtcvasc(char *str, timestamp *ts);
The function receives the string to parse (str) and a pointer to the timestamp variable that should hold the result of the operation (ts). The function returns 0 on success and a negative value in case of error. Internally this function uses the section 3.8.3 The timestamp type function. See the reference there for a table with example inputs.
dtcvfmtasc
Parses a timestamp from its textual representation in ANSI standard using a format mask into a timestamp variable.
dtcvfmtasc(char *inbuf, char *fmtstr, timestamp *dtvalue)
The function receives the string to parse (inbuf), the format mask to use (fmtstr) and a pointer to the timestamp variable that should hold the result of the operation (ts). This functions is implemented by means of the section 3.8.3 The timestamp type. See the documentation there for a list of format specifiers that can be used. The function returns 0 on success and a negative value in case of error.
dtsub
Subtract one timestamp from another and return a variable of type interval.
int dtsub(timestamp *ts1, timestamp *ts2, interval *iv);
The function will subtract the timestamp variable that ts2 points to from the timestamp variable that ts1 points to and will store the result in the interval variable that iv points to. Upon success, the function returns 0 and a negative value if an error occurred.
dttoasc
Convert a timestamp variable to a C char* string.
int dttoasc(timestamp *ts, char *output);
The function receives a pointer to the timestamp variable to convert (ts) and the string that should hold the result of the operation output). It converts ts to its textual representation in the ANSI SQL standard which is defined to be YYYY-MM-DD HH:MM:SS. Upon success, the function returns 0 and a negative value if an error occurred.
dttofmtasc
Convert a timestamp variable to a C char* using a format mask.
int dttofmtasc(timestamp *ts, char *output, int str_len,
 char *fmtstr);
The function receives a pointer to the timestamp to convert as its first argument (ts), a pointer to the output buffer (output), the maximal length that has been allocated for the output buffer (str_len) and the format mask to use for the conversion (fmtstr). Upon success, the function returns 0 and a negative value if an error occurred. Internally, this function uses the section 3.8.3 The timestamp type function. See the reference there for information on what format mask specifiers can be used.
intoasc
Convert an interval variable to a C char* string.
int intoasc(interval *i, char *str);
The function receives a pointer to the interval variable to convert (i) and the string that should hold the result of the operation str). It converts i to its textual representation in the ANSI SQL standard which is defined to be YYYY-MM-DD HH:MM:SS. Upon success, the function returns 0 and a negative value if an error occurred.
rfmtlong
Convert a long integer value to its textual representation using a format mask.
int rfmtlong(long lng_val, char *fmt, char *outbuf);
The function receives the long value lng_val, the format mask fmt and a pointer to the output buffer outbuf. It converts the long value according to the format mask to its textual representation. The format mask can be composed of the following format specifying characters:
  • * (asterisk) - if this position would be blank otherwise, fill it with an asterisk.
  • & (ampersand) - if this position would be blank otherwise, fill it with a zero.
  • # - turn leading zeroes into blanks.
  • < - left-justify the number in the string.
  • , (comma) - group numbers of four or more digits into groups of three digits separated by a comma.
  • . (period) - this character separates the whole-number part of the number from the fractional part.
  • - (minus) - the minus sign appears if the number is a negative value.
  • + (plus) - the plus sign appears if the number is a positive value.
  • ( - this replaces the minus sign in front of the negative number. The minus sign will not appear.
  • ) - this character replaces the minus and is printed behind the negative value.
  • $ - the currency symbol.
rupshift
Convert a string to upper case.
void rupshift(char *str);
The function receives a pointer to the string and transforms every lower case character to upper case.
byleng
Return the number of characters in a string without counting trailing blanks.
int byleng(char *str, int len);
The function expects a fixed-length string as its first argument (str) and its length as its second argument (len). It returns the number of significant characters, that is the length of the string without trailing blanks.
ldchar
Copy a fixed-length string into a null-terminated string.
void ldchar(char *src, int len, char *dest);
The function receives the fixed-length string to copy (src), its length (len) and a pointer to the destination memory (dest). Note that you need to reserve at least len+1 bytes for the string that dest points to. The function copies at most len bytes to the new location (less if the source string has trailing blanks) and adds the null-terminator.
rgetmsg
int rgetmsg(int msgnum, char *s, int maxsize);
This function exists but is not implemented at the moment!
rtypalign
int rtypalign(int offset, int type);
This function exists but is not implemented at the moment!
rtypmsize
int rtypmsize(int type, int len);
This function exists but is not implemented at the moment!
rtypwidth
int rtypwidth(int sqltype, int sqllen);
This function exists but is not implemented at the moment!
rsetnull
Set a variable to NULL.
int rsetnull(int t, char *ptr);
The function receives an integer that indicates the type of the variable and a pointer to the variable itself that is casted to a C char* pointer. The following types exist:
  • CCHARTYPE - For a variable of type char or char*
  • CSHORTTYPE - For a variable of type short int
  • CINTTYPE - For a variable of type int
  • CBOOLTYPE - For a variable of type boolean
  • CFLOATTYPE - For a variable of type float
  • CLONGTYPE - For a variable of type long
  • CDOUBLETYPE - For a variable of type double
  • CDECIMALTYPE - For a variable of type decimal
  • CDATETYPE - For a variable of type date
  • CDTIMETYPE - For a variable of type timestamp
Here is an example of a call to this function:
$char c[] = "abc       ";
$short s = 17;
$int i = -74874;

rsetnull(CCHARTYPE, (char *) c);
rsetnull(CSHORTTYPE, (char *) &s);
rsetnull(CINTTYPE, (char *) &i);
risnull
Test if a variable is NULL.
int risnull(int t, char *ptr);
The function receives the type of the variable to test (t) as well a pointer to this variable (ptr). Note that the latter needs to be casted to a char*. See the function section 3.9.2 Additional functions for a list of possible variable types. Here is an example of how to use this function:
$char c[] = "abc       ";
$short s = 17;
$int i = -74874;

risnull(CCHARTYPE, (char *) c);
risnull(CSHORTTYPE, (char *) &s);
risnull(CINTTYPE, (char *) &i);
ISBN 0954612035PostgreSQL Reference Manual - Volume 2 - Programming GuideSee the print edition