java中怎麽實現階乘,如計算1~100的階乘

壹.壹般算法(循環)

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public class Test {

public static void main(String[] args) {

int result = 1;

for (int i = 1; i <= 100; i++) {

result *= i;

}

System.out.println(result);

}

}

public class Test {

public static void main(String[] args) {

int result = 1;

for (int i = 1; i <= 100; i++) {

result *= i;

}

System.out.println(result);

}

}

輸出結果為0，因為int無法保存下100的階乘的結果，100的階乘的長度至少大於50位，也要大於long,double

二.使用BigInteger大容量運算類

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import java.math.BigInteger;

public class Test {

public static void main(String[] args) {

BigInteger result = new BigInteger("1");//為result賦初始值，為1

for (int i = 1; i <= 100; i++) {

BigInteger num = new BigInteger(String.valueOf(i));

result = result.multiply(num);//調用自乘方法

}

System.out.println(result);//輸出結果

System.out.println(String.valueOf(result).length());//輸出長度

}

}

import java.math.BigInteger;

public class Test {

public static void main(String[] args) {

BigInteger result = new BigInteger("1");//為result賦初始值，為1

for (int i = 1; i <= 100; i++) {

BigInteger num = new BigInteger(String.valueOf(i));

result = result.multiply(num);//調用自乘方法

}

System.out.println(result);//輸出結果

System.out.println(String.valueOf(result).length());//輸出長度

}

}

計算結果為：93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000

產度:158