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Chapter 5 - Text Utilities / Text Utilities Reference

Routines / Comparing Strings for Equality

EqualString

The EqualString function compares two Pascal strings for equality, using the comparison rules of the Macintosh file system. The comparison performed by EqualString is a simple, character-by-character value comparison. This function does not make use of any script or language information; it assumes the use of a Roman script system.

FUNCTION EqualString (aStr, bStr: Str255;
                      caseSens, diacSens: Boolean): Boolean;

aStr

One of the Pascal strings to be compared.

bStr

The other Pascal string to be compared.

caseSens

A flag that indicates how to handle case-sensitive information during the comparison. If the value of caseSens is TRUE, uppercase characters are distinguished from the corresponding lowercase characters. If it is FALSE, case information is ignored.

diacSens

A flag that indicates how to handle information about diacritical marks during the string comparison. If the value of diacSens is TRUE, characters with diacritical marks are distinguished from the corresponding characters without diacritical marks during the comparison. If it is FALSE, diacritical marks are ignored.

DESCRIPTION

EqualString returns TRUE if the two strings are equal and FALSE if they are not equal. If its value is TRUE, EqualString distinguishes uppercase characters from the corresponding lowercase characters. If its value is FALSE, EqualString ignores diacritical marks during the comparison.

SPECIAL CONSIDERATIONS

The EqualString function is not localizable.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the EqualString function are

Trap macro	Selector
_CmpString	$A03C

This trap macro can take optional arguments, each of which changes the default setting used by the macro when it is called without arguments. Each of these arguments corresponds to the Boolean parameters that are used with the Pascal function call. The various permutations of this trap macro are shown below; you must type each exactly as it is shown. The syntax shown here applies to the MPW Assembler; if you are using another development system, be sure to consult its documentation for the proper syntax.

Macro permutation	Value of diacSens	Value of caseSens
_CmpString	FALSE	FALSE
_CmpString ,MARKS	TRUE	FALSE
_CmpString ,CASE	FALSE	TRUE
_CmpString ,MARKS,CASE	TRUE	TRUE

The registers on entry and exit for this routine are

Registers on entry
A0	pointer to first character of the first string
A1	pointer to first character of the second string
D0	high-order word: number of bytes in the first string low-order word: number of bytes in the second string

Registers on exit
D0	long word result: 0 if strings are equal, 1 if strings are not equal