Default_Field_Descriptors

Default field descriptor values are as follows:

Field Descriptor List Element w d e ---------------------------------------------------------- I,O,Z BYTE,INTEGER*1,LOGICAL*1 7 I,O,Z INTEGER*2,LOGICAL*2 7 I,O,Z INTEGER*4,LOGICAL*4 12 O,Z REAL*4 12 O,Z REAL*8 23 O,Z REAL*16 44 O,Z CHARACTER*n MAX(7,3*n) L LOGICAL*1,LOGICAL*2, 2 LOGICAL*4 F,E,G,D REAL,COMPLEX*8 15 7 2 F,E,G,D REAL*4,COMPLEX*16 25 16 2 F,E,G,D REAL*16 42 33 3 A LOGICAL*1 1 A LOGICAL*2,INTEGER*2 2 A LOGICAL*4,INTEGER*4 4 A REAL*8,COMPLEX*8 8 A REAL*8,COMPLEX*16 8 A REAL*16 16 A CHARACTER*n n

General_Form

FORMAT (q1 f1s1 f2s2 ... fnsn qn)

qn Is zero or more slash (/) record terminators. fn Is a field descriptor, an edit descriptor, or a group of field and edit descriptors enclosed in parentheses. sn Is a field separator (a comma or slash). A comma can be omitted in the following cases:

o Between a P edit descriptor and an immediately following F, E, D, or G edit descriptor.

o Before or after a slash (/) record terminator.

o Before or after a colon (_:) edit descriptor.

The "field descriptor" has one of the following forms:

[r]c [r]cw [r]cw.m [r]cw.d[Ee]

r Is the optional repeat count. (If you omit "r", the repeat count is assumed to be 1.) c Is a format code (I,O,Z,F,E,D,G,L, or A). w Is the external field width in characters. Each data item in the external medium is called an external field. m Is the minimum number of characters that must appear in the field (including leading zeros). d Is the number of characters to the right of the decimal point. E Is an exponent field. e Is the number of characters in the exponent.

A group of field descriptors can be formed by enclosing a format specifier in parentheses and optionally preceding the group with a repeat count (defaults to 1). Separate a group from other format specifiers or groups with field separators or record terminators. Groups can be nested to a depth of 8.

The entire format specifier must be enclosed in parentheses.

The ranges for "r", "w", "m", "d", and "e" are as follows:

Term Range ---- __________ r 1 to 32767 (2**15-1) w 1 to 32767 m 0 to 255 (2**8-1) d 0 to 255 e 1 to 255

The "d" and "e" terms are required in some field descriptors and are invalid in others.

The terms must all be unsigned integer constants or variable format expressions.

You cannot use PARAMETER constants for "r", "w", "m", "d", or "e".

The "edit descriptor" has one of the following forms:

c [n]c c[n]

c Is a format code (X,T,TL,TR,SP,SS,S,BN,BZ,P,H,Q,'...' $, or :). n Is the optional number of characters or character positions.

The term "n" must be an unsigned integer constant (for format code P, it can be signed or unsigned) or a variable format expression.

The value of "n" for P must be within the range -128 to 127.

For all other format codes, the value of "n" must be within the range 1 through 32767 (2**15-1); above 32767, you receive an error. Actual useful ranges can be constrained by record sizes (RECL) and the file system.

Format_Descriptors

Field descriptor -- Defines the size and format of a data item. Each field descriptor corresponds to the next data item in the statement's I/O list.

Edit descriptor -- Specifies editing functions to be performed on data items.

Format descriptors are generally separated by commas, but you can also use the slash (/) record terminator to separate them. A slash terminates input or output of the current record and initiates a new record; for example:

WRITE (6,40) K,L,M,N,O,P 40 FORMAT (3I6.6/I6,2F8.4)

The preceding statements are equivalent to the following:

WRITE (6,40) K,L,M 40 FORMAT (3I6.6) WRITE (6,50) N,O,P 50 FORMAT (I6,2F8.4)

Multiple slashes cause the system to bypass input records or output blank records. If "n" consecutive slashes appear between two field or edit descriptors, (n-1) records are skipped on input, or (n-1) blank records are output. The first slash terminates the current record. The second slash terminates the first skipped or blank record, and so on.

However, "n" slashes at the beginning or end of a format specification result in "n" skipped or blank records. This is because the opening and closing parentheses of the format specification are themselves a record initiator and terminator, respectively.

Repeat_Count

For example, the following two statements are equivalent:

20 FORMAT (E12.4,E12.4,E12.4,I5,I5,I5,I5) 20 FORMAT (3E12.4,4I5)

Similarly, you can apply a group of field descriptors repeatedly to data fields by enclosing these field descriptors in parentheses and preceding them with an unsigned integer constant. The integer constant is called a group repeat count. For example, the following two statements are equivalent:

50 FORMAT (I8,I8,F8.3,E15.7,F8.3,E15.7,F8.3,E15.7,I5,I5) 50 FORMAT (2I8,3(F8.3,E15.7),2(I5))

An H or Q field descriptor, which could not otherwise be repeated, can be enclosed in parentheses and treated as a group repeat specification.

Reversion

In format reversion, the current record is terminated, a new one is initiated, and format control reverts to the group repeat specification whose opening parenthesis matches the next-to-last closing parenthesis of the format specification. If the format does not contain a group repeat specification, format control returns to the initial opening parenthesis of the format specification. Format control continues from that point.

Variable_Format_Expressions

20 FORMAT (I<J+1>)

When the format is scanned, the preceding statement performs an integer (I) data transfer with a field width of J+1. The expression is reevaluated each time it is encountered in the normal format scan.

The following rules apply to variable format expressions:

- If the expression is not of integer data type, it is converted to integer data type before being used. - The expression can be any valid Fortran expression, including function calls and references to dummy arguments. - The value of a variable format expression must obey the restrictions on magnitude applying to its use in the format, or an error occurs. - Variable format expressions are not permitted in run-time formats.

Variable format expressions are evaluated each time they are encountered in the scan of the format. If the value of the variable used in the expression changes during the execution of the I/O statement, the new value is used the next time the format item containing the expression is processed.

Field

NOTE: Transfer complex numbers as two real (F, E, D, or G) numbers.

Edit

On input, this specifier transfers the specified characters from the external field.

On output, this specifier transfers the specified characters to the record.

Carriage__Control

The I/O system recognizes the characters listed below as carriage control characters and does not print them.

Character Meaning --------- ------- '+' Overprinting: starts output at the beginning of the current line and returns to the left margin after printing.

' ' Single spacing: starts output at the beginning of the next line.

'0' Double spacing: skips a line before starting output.

'1' Paging: starts output at the top of a new page

'$' Prompting: starts output at the beginning of the next line and does not return to the left margin after printing

ASCII NULL Overprinting with no advance: starts output at the beginning of the current line and does not return to the left margin after printing. (ASCII NULL is specified as CHAR(0).)

Any character other than those listed above is interpreted as a space and is deleted from the print line. If you accidentally omit a carriage control character, the first character of the record is not printed.

$

In a format specification, the dollar sign character ($) modifies the carriage control specified by the first character of the record. It only affects the files for which the 'FORTRAN' carriage control attribute is in effect.

In an input statement, the $ descriptor is ignored.

In an output statement, the following rules apply:

- If the first character of the record is 0 or 1, the $ descriptor is ignored. - If the first character of the record is a space, the $ descriptor suppresses carriage return. However, if the first character in the record is a plus sign (+), the $ descriptor causes the output to begin at the end of the previous line and leaves the print position at the end of the line.

For terminal I/O, whenever carriage control and line feed are suppressed by the $ descriptor, a typed response follows output on the same line.

:

If the corresponding I/O list element has a character data type, character data is transmitted. If it has any other data type, Hollerith data is transmitted. The value of "w" must be less than or equal to 32767.

On input, transfers "w" characters or Hollerith values from the external record and assigns them to the corresponding list element. If the input value contains fewer characters than "w", it is padded on the right with blanks. If the input value contains excessive characters, it is truncated on the left.

If the variable is numeric, the ASCII value of each character is placed in each byte of the variable, starting at the low-order byte.

On output, transfers the contents of the corresponding I/O list element to an external field "w" characters long. If the output value contains fewer characters than "w", it is padded on the left with blanks. If the output value contains excess characters, it is truncated on the right (for numbers, the high-order bytes are lost).

If the output value is numeric or untyped, the ASCII value of each byte of the variable, starting at the low-order byte, is transferred to the record.

The "w" can be omitted and defaults to the number of characters in the character variable or the number of bytes in the numeric variable.

BN

Causes embedded and trailing blanks to be ignored within a numeric input field. Leading blanks are always ignored, and an all blank field is always treated as zero. The BN descriptor must precede all field descriptors to which it applies.

It affects all following I, O, Z, F, E, D, and G editing (in the same FORMAT statement) during the execution of an output statement.

If the OPEN statement is not used or it is used and BLANK='ZERO' is specified, blanks are converted to zeros. If the OPEN statement is used and either BLANK='NULL' is specified or the BLANK keyword is omitted, blanks are ignored.

BZ

Causes embedded and trailing blanks to be treated as zeros within a numeric input field. (Leading blanks are always ignored.) The BZ descriptor must precede all field descriptors to which it applies.

It affects all following I, O, Z, F, E, D, and G editing (in the same FORMAT statement) during the execution of an output statement.

If the OPEN statement is not used or it is used and BLANK='ZERO' is specified, blanks are converted to zeros. If the OPEN statement is used and either BLANK='NULL' is specified or the BLANK keyword is omitted, nonleading blanks are treated as zeros.

An all blank field is always treated as zero.

D

On input, performs the same as F format.

On output, performs the same as E format, except that the letter D replaces the letter E preceding the exponent and the size of the exponent is fixed at 2.

E

On input, performs the same as F format.

On output, E transfers the value of the corresponding I/O list element, rounded to "d" decimal digits and right-justified to an external field "w" characters long. "d" specifies the size of the fraction and "e" specifies the size of the exponent. If the value does not fill the field, leading spaces are inserted; if the value is too large for the field, the entire field is filled with asterisks.

The term "w" must be large enough to include all the following: a minus sign (when necessary) or a plus sign (if SP editing is in effect), a zero, a decimal point, "d" digits, and an exponent.

Therefore, to accommodate all possible components of the standard form, the term "w" must be greater than or equal to "d"+7; if "e" is present, "w" must be greater than or equal to "d"+"e"+5.

However, "w" can be as small as "d"+5 or "d"+"e"+3 and still allow formatting of the value without error, if optional fields are omitted. In this case, the sign is omitted (if the value is positive and SP editing is not in effect) and the zero to the left of the decimal point is also omitted, if necessary.

F

On input, transfers "w" characters from the external field and assigns them, as a real value, to the corresponding I/O list element (which must be real data type). If the first nonblank character of the external field is a minus sign, the field is treated as a negative value. If the first nonblank character is a plus sign or if no sign appears in the field, the field is treated as a positive value.

If the field contains neither a decimal point nor an exponent, it is treated as a real number of w digits, in which the rightmost "d" digits are to the right of the decimal point, with leading zeros assumed if necessary. If the field contains an explicit decimal point, the location of the decimal point overrides the location specified by the field descriptor. If the field contains an exponent, that exponent is used to establish the magnitude of the value before it is assigned to the list element.

On output, transfers the value of the corresponding I/O list element, rounded to "d" decimal positions and right-justified, to an external field that is "w" characters long. If the value does not fill the field, leading spaces are inserted; if the value is too large for the field, the entire field is filled with asterisks.

The term "w" must be large enough to include all the following: a minus sign (when necessary) or a plus sign (if SP editing is in effect), at least one digit to the left of the decimal point, a decimal point, and "d" digits to the right of the decimal.

Therefore, "w" must be greater than or equal to "d"+3.

G

On input, performs the same as F format.

On output, transfers the value of the corresponding I/O list element, rounded to d decimal positions, and right-justified, to an external field that is "w" characters long. The form in which the value is written is a function of the magnitude of the value. as given below:

Data Magnitude Effective Conversion -------------- -------------------- m < 0.1 Ew.d[Ee] 0.1 <= m < 1.0 F(w-4).d, n(' ') 1.0 <= m < 10.0 F(w-4).(d-1), n(' ') . . . . . . 10**d-2 <= m < 10**d-1 F(w-4).1, n(' ') 10**d-1 <= m < 10**d F(w-4).0, n(' ') m >= 10**d Ew.d[Ee]

The term "w" must be large enough to include all the following: a minus sign (when necessary) or a plus sign (if SP editing is in effect), a decimal point, one digit to the left of the decimal point, "d" digits to the right of the decimal, and either a 4-character or "e"+2-character exponent.

Therefore, "w" must be greater than or equal to "d"+8. If "e" is present, "w" must be greater than or equal to "d"+"e"+6.

H

On input, transfers "n" characters from the external record to the field descriptor itself. The first character appears immediately after the H. Any characters in the field descriptor before the input operation are replaced by the input characters.

On output, transfers "n" characters following the letter H from the field descriptor to the external field.

I

On input, transfers "w" characters from the external field and assigns them, as an integer value, to the corresponding I/O list element (which must be integer or logical data type). The external data must have the form of an integer constant; it cannot contain a decimal point or exponent field.

If the first nonblank character of the external field is a minus sign, the field is treated as a negative value. If the first nonblank character is a plus sign or if no sign appears in the field, the field is treated as a positive value.

On output, transfers the value of the corresponding I/O list element, right-justified, to an external field that is w characters long. If the value does not fill the field, leading spaces are inserted; if the value is too large for the field, the entire field is filled with asterisks. "w" must be large enough to include a possible minus sign. If "m" is present, the external field consists of at least "m" digits and, if necessary, is zero filled on the left.

L

On input, transfers "w" characters from the external field and assigns a logical value to the corresponding I/O list element (which must be integer or logical data type). If the first nonblank characters of the field are T, t, .T, or .t, the value .TRUE. is assigned to the corresponding I/O list element; if the first nonblank characters are F, f, .F, or .f, the value .FALSE. is assigned. An all blank field is assigned the value .FALSE. Any other value in the external field produces an error. The logical constants .TRUE. and .FALSE. are acceptable input forms.

On output, transfers either the letter T (if the value of the corresponding I/O list element is .TRUE.) or the letter F (if the value is .FALSE.) to an external field that is w characters long. The letter T or F is in the rightmost position of the field, preceded by w-1 spaces.

O

On input, transfers "w" characters from the external field and assigns them, as an octal value, to the corresponding I/O list element (which can be any data type). The external field can contain only the numerals 0 though 7; it cannot contain a sign, a decimal point, or exponent field. An all blank field is treated as a value of zero. If the value of the external field exceeds the range of the corresponding list element, an error occurs.

On output, transfers the octal value of the corresponding I/O list element, right-justified, to an external field that is "w" characters long. No signs are transmitted; a negative value is transmitted in internal form. If the value does not fill the field, leading spaces are inserted; if the value is too large for the field, the entire field is filled with asterisks. If "m" is present, the external field consists of at least "m" digits and, if necessary, is zero filled on the left.

"w" must be large enough to include a possible minus sign. If "m" is present, the external field consists of at least "m" digits and, if necessary, is zero filled on the left.

P

The scale factor lets you alter, during input or output, the location of the decimal point both in real values and in the two parts of complex values.

The "n" is a signed or unsigned integer constant, in the range -128 to 127, that specifies the number of positions to the left or right that the decimal point is to move.

A scale factor can appear anywhere in a format specification, but must precede the first F, E, D, or G field descriptor that is to be associated with it and affects all following real field descriptors in the same FORMAT statement (unless another scale factor appears.

On input the scale factor of any of the F, E, D, and G field descriptors multiplies the data by 10**-n and assigns it to the corresponding I/O list element. For example a 2P scale factor multiplies an input value by .01; a -2P multiplies an input value by 100. However, if the external field contains an explicit exponent, the scale factor has no effect.

E, D, or G field descriptors alter the form in which data is transferred. On input a positive scale factor moves the decimal point to the left and a negative scale factor moves the decimal point to the right; on output, the effect is the reverse.

Additional Information on:

• F_field_descriptor
• E_field_descriptor
• D_field_descriptor
• G_field_descriptor

On input, obtains the number of characters remaining in the input record to be transferred during a read operation. The following example uses the Q descriptor to determine the size of the input record:

READ(5,'(Q,A)') LEN, REC(1:LEN)

On output, the Q descriptor has no effect, except that the corresponding I/O item is skipped.

S

Restores the option of producing plus characters (+) in numeric output fields. The S descriptor counters the action of either the SP or SS descriptor by restoring to the processor the discretion of producing plus characters on an optional basis.

This descriptor affects fields all that follow it, until an SP or SS is encountered. The S descriptor affects all following I, F, E, D, and G editing (in the same FORMAT statement) during the execution of an output statement.

SP

Causes the processor to produce a leading plus character (+) in any position where this character would otherwise be optional.

This descriptor affects all (suppress + signs) fields that follow it, until an S or SS is encountered. The SP descriptor affects all following I, F, E, D, and G editing (in the same FORMAT statement) during the execution of an output statement.

SS

Causes the processor to suppress a leading plus character from any position where this character would otherwise be optional. It has the opposite effect of the SP field descriptor.

The SS descriptor affects all following I, F, E, D, and G editing (in the same FORMAT statement) during the execution of an output statement. This descriptor affects all fields that follow it, until an S or SS is encountered.

T

On input, starts the next read operation at the character position (within the record) indicated by position(n). For example, if an input statement reads a record containing:

ABC XYZ

and this record is under the control of the FORMAT statement:

10 FORMAT (T7,A3,T1,A3)

On execution, the input statement would first read the characters XYZ and then read the characters ABC.

On output, starts the next write operation at the character position n in the external record.

The position specified must be an integer in the range 1 through the size of the record.

TL

Indicates that the next character to be transferred to or from a record is the "n"th character to the left of the current character.

The value of "n" must be greater than or equal to 1.

If the value of "n" is greater than or equal to the current character position, the first character in the record is specified.

TR

Indicates that the next character to be transferred to or from a record is the "n"th character to the right of the current character.

The value of "n" must be greater than or equal to 1.

X

The X field descriptor functions the same as the TR field descriptor.

On input, starts the next read operation after skipping "n" character positions. If X is the last format item, it will have no effect.

On output, starts the next write operation after skipping the "n" character positions. Intervening characters are not written over. If X is the last format code executed, it will have no effect.

The position specified must be an integer in the range 1 through the size of the record.

Z

On input, transfers w characters from the external field and assigns them, as a hexadecimal value, to the corresponding I/O list element (which can be any data type). The input value must be in the form of a hexadecimal constant. Each input character corresponds to four bits in the variable, high order to low order. If the input value contains more characters than specified by "w", an error occurs. If the input value contains fewer characters, it is padded with zeros on the left before being converted.

On output, transfers the number of hexadecimal characters specified by "w" from a variable or constant to the record. The rightmost characters represent the low-order bits. If the variable or constant contains more characters than "w" specifies, the value is set to all asterisks (an error occurs). If the variable or constant contains fewer characters, the value is padded on the left with spaces. "m" specifies the minimum number of characters (with zero padding) that the value can contain. "m" must be an integer in the range 1 through 255. "w" must be large enough to include a possible minus sign. If "m" is present, the external field consists of at least "m" digits and, if necessary, is zero filled on the left.