如何仅用字符串实现无限大整数的绝对精确乘法？

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将两个仅由数字字符组成的字符串相乘，返回相乘结果。

javaStringBuilder multiplyTwoIntegerNum(StringBuilder num1, StringBuilder num2) { int length1=num1.length(); int length2=num2.length(); int[] multiplyArray=new int[length1 + length2];

for (int i=length1 - 1; i >=0; i--) { for (int j=length2 - 1; j >=0; j--) { int digit1=num1.charAt(i) - '0'; int digit2=num2.charAt(j) - '0'; int sum=digit1 * digit2 + multiplyArray[i + j + 1]; multiplyArray[i + j + 1]=sum % 10; multiplyArray[i + j] +=sum / 10; } }

StringBuilder result=new StringBuilder(); for (int i=0; i

return result;}

传入两个只有数字字符组成的字符串，返回相乘结果

StringBuilder multiplyTwoIntegerNum(StringBuilder num1, StringBuilder num2){ int length1 = num1.length(); int length2 = num2.length(); int[] multiplyArray = new int[length1 + length2]; for (int i = length1 - 1; i > -1; i--) { for (int j = length2 - 1; j > -1; j--) { multiplyArray[i + j] += (num1.charAt(i) - '0') * (num2.charAt(j) - '0'); } } StringBuilder result = new StringBuilder(); for (int i = multiplyArray.length - 2; i > 0; i--) { int d = multiplyArray[i] % 10; int c = multiplyArray[i] / 10; multiplyArray[i - 1] += c; result.insert(0, d); } result.insert(0, multiplyArray[0]); return result; }