Compose String

Compose output string signal based on specified format and input signals

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Libraries:
Simulink / String

Description

The Compose String block composes output string signal based on the format specifier listed in the Format parameter. The Format parameter determines the number of input signals. If there are multiple inputs, the block constructs the string by combining these multiple inputs in order, and applying the associated format specifier, one format specifier for each input. Each format specifier starts with a percent sign, %, followed by the conversion character. For example, %f formats the input as a floating point output. To supplement the string output, you can also add a character to the format specification. Use this block to compose and format an output string signal from a multiple inputs.

For example, if the Format parameter contains "%s is %f", the block expects two inputs, a string signal and a single or double signal. If the first input is the string "Pi" and the second input is a double value 3.14, the output is "Pi is 3.14".

When a MinGW^® compiler compiles code generated from the block, running the compiled code may produce nonstandard results for floating-point inputs. For example, a numeric input of 501.987 returns the string "5.019870e+002" instead of the expected string "5.019870e+02".

Ports

Input

d — Data for first part of string

scalar

Data for the first part of string, specified as a scalar. The Format parameter determines the port label and the format of the input data. For example, if the first item in the Format parameter is %d, the port label is d.

The data type of the input signal must be compatible with the format specifier in the Format parameter. For more information, see the Format parameter.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

f — Data for second part of string

scalar

Data for the second part of string, specified as a scalar. The Format parameter determines the port label and the format of the input data. For example, if the first item in the Format parameter is %f, the port label is f.

The data type of the input signal must be compatible with the format specifier specified in the Format parameter. For more information, see the Format parameter.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

Port_N — Data for N parts of string

scalar (default)

Data for N parts of string, specified as a scalar. The Format parameter determines the port label and the format of the input data. For example, if the corresponding item in the Format parameter is %f, the port label is f.

The data type of the input signal must be compatible with the format specifier in the Format parameter. For more information, see the Format parameter.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

Output

str — Output string

scalar

Output string composed of inputs, specified as a scalar.

Data Types: string

Parameters

Format — Format input data

"%d %f" (default) | format string | character vector

Format of input data, specified as a format string.

For more information about acceptable format specifiers, see Algorithms.

Programmatic Use

Block Parameter: Format

Type: character vector

Values: '<filename>'

Default: '"%d %f"'

Output data type — Output data type

string (default) | <data type expression>

Output data type, specified using the string data type to specify a string with no maximum length.

To specify a string data type with a maximum length, specify stringtype(N). For example, stringtype(31) creates a string data type with a maximum length of 31 characters.

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. See Specify Data Types Using Data Type Assistant for more information.

Programmatic Use

Block Parameter: OutDataTypeStr

Type: character vector

Values: 'string' | <data type expression>

Default: 'string'

Mode — Category of data

string (default) | scalar

Use the stringtype function, for example, stringtype(255).

Dependency

Clicking the Show data type assistant button enables this parameter.

Block Characteristics

Data Types	double | integer | single | string
Direct Feedthrough	yes
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Algorithms

A formatting specifier starts with a percent sign, %, and ends with a conversion character. The conversion character is required. Optionally, you can specify identifier, flags, field width, precision, and subtype specifiers between % and the conversion character. (Spaces are invalid between specifiers and are shown here only for readability).

The Compose String block uses this format specifier prototype:

%[flags][width][.precision][length]specifier

Conversion Character

This table shows conversion characters to format numeric and character data as text.

Value Type	Conversion	Details
Integer, signed	%d or %i	Base 10
Integer, unsigned	%u	Base 10
	%o	Base 8 (octal)
	%x	Base 16 (hexadecimal), lowercase letters a–f
	%X	Same as %x, uppercase letters A–F
Floating-point number	%f	Floating-point notation (Use a precision operator to specify the number of digits after the decimal point.)
	%e	Exponential notation, such as 3.141593e+00 (Use a precision operator to specify the number of digits after the decimal point.)
	%E	Same as %e, but uppercase, such as 3.141593E+00 (Use a precision operator to specify the number of digits after the decimal point.)
	%g	The more compact of %e or %f, with no trailing zeros (Use a precision operator to specify the number of significant digits.)
	%G	The more compact of %E or %f, with no trailing zeros (Use a precision operator to specify the number of significant digits.)
String	%s	The type of the output text is the same as the type of Format.

Optional Operators

The optional identifier, flags, field width, precision, and operators further define the format of the output text.

• Flags

  '–'	Left-justify. Works with all specifiers. Example: %-5.2f Example: %-10s
  '+'	Always print a sign character (+ or –) for any numeric value. Works with all specifiers except u, o, x, X, and s. Example: %+5.2f Right-justify text. Example: %+10s
  ' '	Insert a space before the value. Works with all specifiers except u, o, x, X, and s. Example: % 5.2f
  '0'	Pad to field width with zeros before the value. Works with all specifiers except s. Example: %05.2f
  '#'	Modify selected numeric conversions: For %o, %x, or %X, print 0, 0x, or 0X prefix. For %f, %e, or %E, print decimal point even when precision is 0. For %g or %G, do not remove trailing zeros or decimal point. Works with all specifiers except d, i, u, and s. Example: %#5.0f

• Field Width

  Minimum number of characters to print.

  The function pads to field width with spaces before the value unless otherwise specified by flags.

• Precision

  For %f, %e, or %E	Number of digits to the right of the decimal point Example: '%.4f' prints pi as '3.1416'
  d, i, o, u, x, X	Minimum number of digits to be written. Outputs shorter than the specified precision are padded with leading zeros. Example: "%.4d" prints 5 as '0005'
  For %g or %G	Number of significant digits Example: '%.4g' prints pi as '3.142'
  s	Maximum number of characters to be written to the output. Example: "%.2s" prints "Hello!" as "He"

  Note

  If you specify a precision operator for floating-point values that exceeds the precision of the input numeric data type, the results might not match the input values to the precision you specified. The result depends on your computer hardware and operating system.

Text Before or After Formatting Operators

Special Character	Representation
Single quotation mark	''
Percent character	%%
Backslash	\\
Alarm	\a
Backspace	\b
Form feed	\f
New line	\n
Carriage return	\r
Horizontal tab	\t
Vertical tab	\v
Character whose Unicode® numeric value can be represented by the hexadecimal number, N	\xN Example: sprintf('\x5A') returns 'Z'
Character whose Unicode numeric value can be represented by the octal number, N	\N Example: sprintf('\132') returns 'Z'

Format can also include additional text before a percent sign, %, or after a conversion character. The text can be:

• Ordinary text to print.

• Special characters that you cannot enter as ordinary text. This table shows how to represent special characters in formatSpec.

Length Specifiers

The Format String block supports the h and l length subspecifiers. These specifiers can change according to the Configuration Parameters > Hardware Implementation > Number of bits settings

Length	d i	u o x X	f e E g G	s
No length specifier	int	unsigned int	double (default), single	string
h	short	unsigned short	—	—
l	long	unsigned long	—	—

Note for Specifiers That Specify Integer Data Types (d, i, u, o, x, X)

Target int, long, and short type sizes are controlled by settings in the Configuration Parameters > Hardware Implementation pane. For example, if the target int is 32 bits and the specifier is %u, then the expected input type will be uint32. However, the input port accepts any built-in integer type of that size or smaller with the %u specifier

Notes for Specifiers That Specify Floating Point Data Types (f, e, E, g, F)

• Do not use l and h with these specifiers. Do not use the length subspecifier (for example, %f is allowed, but %hf and %lf are not allowed).

• Ports that correspond with these specifiers accept both single and double data types.

Note for Specifiers That Specify the String Data Type (s)

• The s specifier does not work with the l or h subspecifiers, and only accepts a string input data type.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2018a