countLetter method
The countLetter extension counts the occurrences of a specific single letter within a given text here's and Example:
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String longText = "This is an example text with ab letters and ab words. It also contains abbreviations like abc and abcd. The rabbit jumped over the ab fence.";
int count = longText.countLetter("a");
print("The sequence 'a' appears $count times in the text.");
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Implementation
int countLetter(String targetLetter) {
if (targetLetter.length > 1) {
throw ErrorDescription(
"The method failed because you pass more than single letter in targetLetter property");
}
return split('').where((char) => char == targetLetter).length;
}