Formatting Text - MATLAB & Simulink (2024)

Conversion Character

The conversion character specifies the notation of the output. It consistsof a single character and appears last in the format specifier.

For example, format the number 46 using different conversioncharacters to display the number in decimal, fixed-point, exponential,and hexadecimal formats.

A = 46*ones(1,4);txt = sprintf('%d %f %e %X', A)

txt = '46 46.000000 4.600000e+01 2E'

Subtype

The subtype field is a single alphabetic character that immediatelyprecedes the conversion character. Without the subtype field, theconversion characters %o, %x, %X,and %u treat input data as integers. To treat inputdata as floating-point values instead and convert them to octal, decimal,or hexadecimal representations, use one of following subtype specifiers.

Precision

The precision field in a formatting operator is a nonnegativeinteger that immediately follows a period. For example, in the operator %7.3f,the precision is 3. For the %g operator,the precision indicates the number of significant digits to display.For the %f, %e, and %E operators,the precision indicates how many digits to display to the right ofthe decimal point.

Display numbers to different precisions using the precisionfield.

txt = sprintf('%g %.2g %f %.2f', pi*50*ones(1,4))

txt = '157.08 1.6e+02 157.079633 157.08'

While you can specify the precision in a formatting operatorfor input text (for example, in the %s operator),there is usually no reason to do so. If you specify the precisionas p, and p is less than thenumber of characters in the input text, then the output contains onlythe first p characters.

Field Width

The field width in a formatting operator is a nonnegative integerthat specifies the number of digits or characters in the output whenformatting input values. For example, in the operator %7.3f,the field width is 7.

Specify different field widths. To show the width for each output,use the | character. By default, the output textis padded with space characters when the field width is greater thanthe number of characters.

txt = sprintf('|%e|%15e|%f|%15f|', pi*50*ones(1,4))

txt = '|1.570796e+02| 1.570796e+02|157.079633| 157.079633|'

When used on text input, the field width can determine whetherto pad the output text with spaces. If the field width is less thanor equal to the number of characters in the input text, then it hasno effect.

txt = sprintf('%30s', 'Pad left with spaces')

txt = ' Pad left with spaces'

Flags

Optional flags control additional formatting of the output text.The table describes the characters you can use as flags.

Right- and left-justify the output. The default behavior isto right-justify the output text.

txt = sprintf('right-justify: %12.2f\nleft-justify: %-12.2f',... 12.3, 12.3)

txt = 'right-justify: 12.30 left-justify: 12.30 '

Display a + sign for positive numbers. Thedefault behavior is to omit the leading + signfor positive numbers.

txt = sprintf('no sign: %12.2f\nsign: %+12.2f',... 12.3, 12.3)

txt = 'no sign: 12.30 sign: +12.30'

Pad to the left with spaces and zeroes. The default behavioris to pad with spaces.

txt = sprintf('Pad with spaces: %12.2f\nPad with zeroes: %012.2f',... 5.2, 5.2)

txt = 'Pad with spaces: 5.20 Pad with zeroes: 000000005.20'

Value Identifiers

By default, functions such as sprintf insertvalues from input arguments into the output text in sequential order.To process the input arguments in a nonsequential order, specify theorder using numeric identifiers in the format specifier. Specify nonsequentialarguments with an integer immediately following the % sign,followed by a $ sign.

sprintf('%s %s %s',... '1st','2nd','3rd')ans = '1st 2nd 3rd'

sprintf('%3$s %2$s %1$s',... '1st','2nd','3rd')ans = '3rd 2nd 1st'

Special Characters

Special characters can be part of the output text. But becausethey cannot be entered as ordinary text, they require specific charactersequences to represent them. To insert special characters into outputtext, use any of the character sequences in the table.

Rules for Formatting Precision and Field Width

The figure illustrates how the field width and precision settingsaffect the output of the formatting functions. In this figure, thezero following the % sign in the formatting operatormeans to add leading zeroes to the output text rather than space characters.

Specify Field Width and Precision Outside Format Specifier

You can specify the field width and precision using values froma sequential argument list. Use an asterisk (*)in place of the field width or precision fields of the formattingoperator.

For example, format and display three numbers. In each case,use an asterisk to specify that the field width or precision comefrom input arguments that follow the format specifier.

txt = sprintf('%*f %.*f %*.*f',... 15,123.45678,...  3,16.42837,...  6,4,pi)

txt = ' 123.456780 16.428 3.1416'

The table describes the effects of each formatting operatorin the example.

You can mix the two styles. For example, get the field widthfrom the following input argument and the precision from the formatspecifier.

txt = sprintf('%*.2f', 5, 123.45678)

txt = '123.46'

Specify Numbered Identifiers in Width and Precision Fields

You also can specify field width and precision as values froma nonsequential argument list, using an alternate syntax shown inthe figure. Within the formatting operator, specify the field widthand precision with asterisks that follow numbered identifiers and $ signs.Specify the values of the field width and precision with input argumentsthat follow the format specifier.

For example, format and display three numbers. In each case,use a numbered identifier to specify that the field width or precisioncome from input arguments that follow the format specifier.

txt = sprintf('%1$*4$f %2$.*5$f %3$*6$.*7$f',... 123.45678, 16.42837, pi, 15, 3, 6, 4)

txt = ' 123.456780 16.428 3.1416'

The table describes the effect of each formatting operator inthe example.