atoi

Author: u2

src/atoi.rs

@@ -0,0 +1,48 @@
+pub fn atoi(string: &str) -> Option<i32> {
+    let mut f: bool = false;
+    let mut res: Vec<char> = Vec::with_capacity(string.chars().count());
+    for c in string.chars().into_iter() {
+        match c {
+            '-' | '+' => res.push(c),
+            '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' => {
+                res.push(c);
+                f = true;
+            }
+            ' ' => {}
+            _ => {
+                if !f {
+                    return None;
+                }
+            }
+        }
+    }
+    if f {
+        Some(res.into_iter().collect::<String>().parse::<i32>().unwrap())
+    } else {
+        None
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::atoi;
+
+    #[test]
+    fn test_atoi() {
+        assert_eq!(atoi("123"), Some(123));
+
+        assert_eq!(atoi(" 123"), Some(123));
+
+        assert_eq!(atoi(" +123"), Some(123));
+
+        assert_eq!(atoi(" -123"), Some(-123));
+
+        assert_eq!(atoi(" -a123"), None);
+
+        assert_eq!(atoi(" -123a44"), Some(-12344));
+
+        assert_eq!(atoi(" -xfd"), None);
+
+        assert_eq!(atoi("    "), None);
+    }
+}

src/lib.rs

@@ -7,3 +7,4 @@ pub mod find_median_sorted_arrays;
 pub mod longest_palindrome;
 pub mod zigzag_conversion;
 pub mod reverse_integer;
+pub mod atoi;