String Comparison
D overloads the binary relational operators and permits them to be used
for string comparisons as well as integer comparisons. The relational operators
perform string comparison whenever both operands are of type string,
or when one operand is of type string and the other operand
can be promoted to type string, as described in String Assignment. All of
the relational operators can be used to compare strings:
Table 2-14 D Relational Operators
for Strings
<
| left-hand operand is less than right-operand
|
<=
| left-hand operand is less than or equal to right-hand operand
|
>
| left-hand operand is greater than right-hand operand
|
>=
| left-hand operand is greater than or equal to right-hand operand
|
==
| left-hand operand is equal to right-hand operand
|
!=
| left-hand operand is not equal to right-hand operand
|
|
As with integers, each operator evaluates to a value of type int which
is equal to one if the condition is true, or zero if it is false.
The relational operators compare the two input strings byte-by-byte,
similar to the C library routine strcmp(3C). Each byte
is compared using its corresponding integer value in the ASCII character set,
as shown in ascii(5), until a null byte is read or
the maximum string length is reached. Some example D string comparisons and
their results are:
"coffee" < "espresso"
| ... returns 1 (true)
|
"coffee" == "coffee"
| ... returns 1 (true)
|
"coffee" >= "mocha"
| ... returns 0 (false)
|
|