LeetCode – String to Integer (atoi) (Java)
Implement atoi to convert a string to an integer.
Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.
Analysis
The following cases should be considered for this problem:
1. null or empty string 2. white spaces 3. +/ sign 4. calculate real value 5. handle min & max
Java Solution
public int atoi(String str) { if (str == null  str.length() < 1) return 0; // trim white spaces str = str.trim(); char flag = '+'; // check negative or positive int i = 0; if (str.charAt(0) == '') { flag = ''; i++; } else if (str.charAt(0) == '+') { i++; } // use double to store result double result = 0; // calculate value while (str.length() > i && str.charAt(i) >= '0' && str.charAt(i) <= '9') { result = result * 10 + (str.charAt(i)  '0'); i++; } if (flag == '') result = result; // handle max and min if (result > Integer.MAX_VALUE) return Integer.MAX_VALUE; if (result < Integer.MIN_VALUE) return Integer.MIN_VALUE; return (int) result; } 
<pre><code> String foo = "bar"; </code></pre>

Sékine Coulibaly

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uee