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public class StringToInteger {
public int myAtoi(String str) {
if (str == null || str.trim().isEmpty()) {
return 0;
}
str = str.trim();
double result = 0;
int offSet = 0;
boolean positive = true;
char c = str.charAt(0);
if (c == '-') {
positive = false;
offSet++;
}
if (c == '+') {
offSet++;
}
while (offSet < str.length() && isNumber(str.charAt(offSet))) {
result = result * 10 + (str.charAt(offSet) - '0');
offSet++;
}
result = positive ? result : -1 * result;
if (result > Integer.MAX_VALUE) {
return Integer.MAX_VALUE;
}
if (result < Integer.MIN_VALUE) {
return Integer.MIN_VALUE;
}
return (int) result;
}
private boolean isNumber(char c) {
return c >= '0' && c <= '9';
}
@Test
public void test() {
System.out.println(myAtoi("-212121"));
System.out.println(myAtoi(String.valueOf(Integer.MAX_VALUE)));
System.out.println(myAtoi(String.valueOf(Integer.MIN_VALUE)));
System.out.println(myAtoi("-2147483649"));
System.out.println(myAtoi("2147483649"));
}
}
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