Empty String - Use in Programming Languages

Use in Programming Languages

In most programming languages, strings are a data type. Individual strings are typically stored in consecutive memory locations. This means that the same string (for example the empty string) could be stored in two different places in memory. (Note that even a string of length zero can require memory to store it, depending on the format being used.) In this way there could be multiple empty strings in memory, in contrast with the formal theory definition, for which there is only one possible empty string. However, a string comparison function would indicate that all of these empty strings are equal to each other.

The empty string is distinct from a null reference (or null pointer) because a null reference does not point to any string at all, not even the empty string. A null reference is likely to cause an error if one tries to perform any operation on it, but an empty string is less likely to do so. The empty string is a legitimate string, upon which most string operations should work. Some languages treat some or all of the following in similar ways, which can lessen the danger: empty strings, null references, the integer 0, the floating point number 0, the boolean value false, the ascii character NUL, or other such values.

The empty string is usually represented similarly to other strings. In implementations with string terminating character (null-terminated strings or plain text lines), the empty string is indicated by the immediate use of this terminating character.