Scan String

Scan input string and convert to signals per specified format

• 

Libraries:
Simulink / String

Description

The Scan String block scans an input string and converts it to signals per the format specified by the Format parameter. The block converts values to their decimal (base 10) representation and outputs the results as numeric or string signals. Use this block when you want to deconstruct a string, for example a sentence, into its individual components. For example, if the Format parameter is set to "%s is %f.", the block outputs two parts, a string signal and a single signal. If the input is the string "Pi is 3.14", the two outputs are "Pi" and "3.14".

Note

If you specify a numeric display format that is not large enough to display all the digits of a value, the displayed values may lose precision. The result depends on your computer hardware and operating system.

The Scan String, String to Double, and String to Single blocks are identical blocks. When configured for String to Double, the block converts the input string signal to a double numerical output. When configured for String to Single, the block converts the input string signal to a single numerical output.

For code generation, configure models that contain this block for non-finite number support by selecting the Configuration Parameters > Code Generation > Interface > Support non-finite numbers check box.

Ports

Input

Port_1 — Input string

scalar

Input string, specified as a scalar.

Data Types: string

Output

d — Output data whose format matches %d format

scalar

Output data whose format matches the specified format, defined as a scalar. Total maximum number of outputs is 128.

If the block cannot match an input string to a format operator specified in Format, it returns a warning and outputs an appropriate value (0 or "") for each unmatched format operator.

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

f — Output data whose format matches %f format

scalar

Output data whose format matches the %f format, specified as a scalar. Total maximum number of outputs is 128.

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

Port_N — Output data whose format matches N format

scalar

Output data whose format matches N format, specified as a scalar. Total maximum number of outputs is 128.

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

Parameters

Format — Format operator for input

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

Format operator for input, specified as a scalar. If the block cannot match the input string with the specified format, it returns 0. The return of 0 differs from the sscanf function return, which is an empty matrix if the function cannot match the input with the specified format.

• For the String to Double block, this parameter has a default value of %lf.

• For the String to Single block, this parameter has a default value of %f.

For more information about acceptable format operators, see the Algorithms section.

Programmatic Use

Block Parameter: Format

Type: character vector

Values: '<filename>'

Default: '"%d %f"'

Block Characteristics

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

Algorithms

The Scan String block uses this format specifier prototype:

%[width][length]specifier

Numeric Fields

This table lists available conversion specifiers to convert text to numeric outputs. The block converts values to their decimal (base 10) representation.

Output Port Data Type	Conversion Specifier	Description
Integer, signed	%d	Base 10
Integer, unsigned	%u	Base 10
Floating-point number	%f, %e, or %g	Floating-point values. Input fields can contain NaN (case sensitive). Input fields that represents floating-point numbers can include leading + or - symbols and exponential notation using e or E. The conversion specifiers %f, %e, and %g all treat input fields the same way.

Character Fields

This table lists available conversion specifiers to convert text so that the output is a string.

Character Field Type	Conversion Specifier	Description
String scalar	%s	Read the text until the block encounters white space.
	%c	Read any single character, including white space. To read multiple characters at a time, specify field width. For example, %10c reads 10 characters at a time.
Pattern-matching	%[...]	Read only the characters in the brackets up to the first nonmatching character or white space. Example: %[mus] reads 'summer' as 'summ'.
	%[^...]	Read any characters not in the brackets up to the first matching character or white space. Example: %[^m] reads 'summer' as 'su'.

Optional Operators

• Field Width — To specify the maximum number of digits or text characters to read at a time, insert a number after the percent character. For example, %10s reads up to 10 characters at a time, including white space. %4f reads up to four digits at a time, including the decimal point.

• Literal Text to Ignore — This block must match the specified text immediately before or after the conversion specifier.

  Example: Hell%s reads "Hello!" as "o!".

Length Specifiers

The Scan 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	i	u	f e g	s c […] [^...]
No length specifier	int	unsigned int	single	string
h	short	unsigned short	—	—
l	long	unsigned long	double	—

Notes for Specifiers that Specify Integer Data Types (d, u)

• 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. For this example, the Scan String block requires that the output type be exactly int32. It cannot be any other data type.

Extended Capabilities

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

Version History

Introduced in R2018a