Parser Capstone

CSV Number Parser

Sum Valid Fields

Parsing often combines splitting, trimming, and conversion while ignoring fields that do not match the target type.

Program

Play the program to choose a CSV line and sum the numeric fields.

line
csv_number_parser.rs
Replay: real traced execution (multi-file project)
fn main() {
    let line = "2,4,6";
    let total = parse_numbers(line);
    println!("total={total}");
}

fn parse_numbers(line: &str) -> i32 {
    line.split(',')
        .filter_map(|part| part.trim().parse::<i32>().ok())
        .sum()
}

fn main() {
    let line = "1, bad, 3";
    let total = parse_numbers(line);
    println!("total={total}");
}

fn parse_numbers(line: &str) -> i32 {
    line.split(',')
        .filter_map(|part| part.trim().parse::<i32>().ok())
        .sum()
}

fn main() {
    let line = "10,20";
    let total = parse_numbers(line);
    println!("total={total}");
}

fn parse_numbers(line: &str) -> i32 {
    line.split(',')
        .filter_map(|part| part.trim().parse::<i32>().ok())
        .sum()
}

  1. line ← "2,4,6"

    1fn main() {2    let lin→ "2,4,6"e = "2,4,6"; //@line="2,4,6", "1, bad, 3", "10,20"3    let total = parse_numbers(lin"2,4,6"e);4    println!("total={total}");

  2. total ← 12

    2    let line = "2,4,6"; //@line="2,4,6", "1, bad, 3", "10,20"3    let tota→ 12l = parse_numbers(lin"2,4,6"e);4    println!("total={total}");5}
    outputtotal=12

  1. line ← "1, bad, 3"

    1fn main() {2    let lin→ "1, bad, 3"e = "1, bad, 3";3    let total = parse_numbers(lin"1, bad, 3"e);4    println!("total={total}");

  2. total ← 4

    2    let line = "1, bad, 3";3    let tota→ 4l = parse_numbers(lin"1, bad, 3"e);4    println!("total={total}");5}
    outputtotal=4

  1. line ← "10,20"

    1fn main() {2    let lin→ "10,20"e = "10,20";3    let total = parse_numbers(lin"10,20"e);4    println!("total={total}");

  2. total ← 30

    2    let line = "10,20";3    let tota→ 30l = parse_numbers(lin"10,20"e);4    println!("total={total}");5}
    outputtotal=30
split `split(',')` creates fields from a comma-separated line.
filter_map `filter_map` keeps successfully parsed numbers and skips invalid fields.
sum `sum` folds the parsed numbers into one total.