Programming techniques - OCRThe use of basic string manipulation

A string is a variable that holds a sequence of one or more alphanumeric characters. It is usually possible to manipulate a string to provide information or to alter the contents of a string.

The following examples use strings:

wordOne = "Computer"
wordTwo = "Science"

Length

The length of a string can usually be determined using the lenstatement. This gives the length as an integer.

len(wordOne) - would give the answer eight, as there are eight characters in the word "Computer"

Character position

It is possible to determine which character features at a position within a string:

wordOne[2] - would give the answer "m", as "m" is the third character in the word “Computer” (remember computers start counting at zero)

wordOne[0,3] - would give "Com", the first three characters in the string

wordOne[3,3] - would give "put", the three characters starting from position three

Upper and lowercase

It is possible to change all letters in a string to either lowercase or uppercase. This can be very useful, for example when checking possible inputs:

topic = "Computer Science"

topic = topic.lower - would give a value for the topic of "computer science"

topic = topic.upper - would give a value for the topic of "COMPUTER SCIENCE"

Concatenation

To concatenate strings means to join them to form another string. For example:

sentence = wordOne + " " + wordTwo - would give "Computer Science"

Alternatively, a string can be lengthened by adding more characters. For example:

wordOne = wordOne + " Science" - would result in the value of wordOne becoming "Computer Science"