Programming and Data Types

Searching and Replacing

MATLAB provides several functions for searching and replacing characters in a string. Consider a string named `label`.

• ```label = 'Sample 1, 10/28/95';
```

The` ``strrep` function performs the standard search-and-replace operation. Use `strrep` to change the date from `'10/28'` to `'10/30'`.

• ```newlabel = strrep(label,'28','30')
newlabel =
Sample 1, 10/30/95
```

`findstr` returns the starting position of a substring within a longer string. To find all occurrences of the string `'amp'` inside `label`

• ```position = findstr('amp',label)
position =
2
```

The position within `label` where the only occurrence of `'amp'` begins is the second character.

The `strtok` function returns the characters before the first occurrence of a delimiting character in an input string. The default delimiting characters are the set of whitespace characters. You can use the `strtok` function to parse a sentence into words; for example,

• ```function all_words = words(input_string)
remainder = input_string;
all_words = '';

while (any(remainder))
[chopped,remainder] = strtok(remainder);
all_words = strvcat(all_words,chopped);
end
```

The `strmatch` function looks through the rows of a character array or cell array of strings to find strings that begin with a given series of characters. It returns the indices of the rows that begin with these characters.

• ```maxstrings = strvcat('max','minimax','maximum')
maxstrings =
max
minimax
maximum

strmatch('max',maxstrings)
ans =
1
3
```

 Categorizing Characters Within a String Regular Expressions