Count characters. Suppose you have a Rust str, and you want to count its characters like Microsoft Word. If we treat each space as a separate character, results are incorrect.
Method notes. In word processors, the logic counts sequential whitespace (like space chars) as single characters. This gives a more real-world estimate of character counts.
Example code. To begin, we introduce 2 Rust functions. The count_chars function is more interesting: it has logic to test for sequential whitespace.
Info In count_chars, we use is_whitespace() to detect space chars. Then on each char, we record whether we encountered a whitespace.
And If the previous char was a whitespace char, and the current also is one, we do not count the current one as a character.
Finally The count_nonspace_chars is simpler—it ignores all characters that are whitespace.
fn count_chars(test: &str) -> i32 {
let mut result = 0;
let mut last_was_space = false;
for c in test.chars() {
// Only count whitespace chars that are not preceded by another whitespace.
if c.is_whitespace() {
if last_was_space == false {
result += 1;
}
last_was_space = true;
} else {
result += 1;
last_was_space = false;
}
}
return result;
}
fn count_nonspace_chars(test: &str) -> i32 {
let mut result = 0;
for c in test.chars() {
// Count all chars that are not whitespace.
if !c.is_whitespace() {
result += 1;
}
}
return result;
}
fn main() {
let test = "There is a cat, my friend. How are you?";
// Test the functions.
let result1 = count_chars(test);
let result2 = count_nonspace_chars(test);
println!("RESULT1: {}", result1);
println!("RESULT2: {}", result2);
}RESULT1: 39
RESULT2: 31
Results note. In my previous research, I found that word processor signore sequential whitespace. And the Rust program results match results of existing methods.
Tip Search for the C# Count Characters method on this site for a complete analysis of word processors.
A summary. It is possible to build functions in Rust that parallel existing software features. Having methods that can give results like this is useful.
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