我正在尝试将一个字符串转换为大整数以进行一些算术计算。然而，当我尝试这样做：
Number("9007199254740993")
我得到了这个意外的结果：
9007199254740992
Number能够处理的整数大小限制所致。Number没有返回正确的值，我得到了"9007199254740993"和"9007199254740992"之间的错误差值。具体来说，我期望得到1，但实际上却得到了0。注意：如果你要处理大数，我建议你使用BigInt（由@Andreas在评论中提出）。
已更新
使用以下代码比较大的正整数（参数应为字符串格式）
function compareBigNumber(num1, num2) {
if (num1 > Number.MAX_SAFE_INTEGER && num2 > Number.MAX_SAFE_INTEGER) {
var newNum1 = num1.split('').reverse();
var newNum2 = num2.split('').reverse();
do {
newNum1.pop();
newNum2.pop();
} while (newNum1[newNum1.length-1] === '0' || newNum2[newNum2.length-1] === '0')
return compareBigNumber(newNum1.reverse().join(''), newNum2.reverse().join(''));
} else if(num1 > Number.MAX_SAFE_INTEGER){
return 'num1 is greater'
} else if (num2 > Number.MAX_SAFE_INTEGER) {
return 'num2 is greater'
}
else {
var num1Int = parseInt(num1);
var num2Int = parseInt(num2);
if (num1Int > num2Int) {
return 'Num1 is greater';
} else if (num2Int > num1Int){
return 'Num2 is greater'
} else {
return 'Num1 is equal to Num2';
}
}
}
console.log(compareBigNumber("9007199254740992", "9007199254740993"))
console.log(compareBigNumber("100000000000000000000", "0"))compareBigNumber("1000000000000000000000", "0") 返回 "Num1 等于 Num2"。看起来你对代码做了一些假设，但在这种情况下不成立。 - FK82如果你不想依赖于BigInt，并且只考虑正整数，那么你也可以自己编写后继测试。完整代码如下所示。
正整数的字符串表示很容易转换为十进制数组，其中索引表示以10为底数的指数。例如"42" ~> [2, 4]（因为42 = 2*10^0 + 4*10^1）。您也可以轻松地将其转换回来。
现在，对于后继测试，您只需要定义增量操作（即带进位的加1）。有了这个，您就可以比较一个数字的增量是否等于未增量的另一个数字（反之亦然）。
// Convert a string representation of positive decimal integer to an array of decimals.
const toArray = numberString => Array.from(numberString, c => parseInt(c))
.reverse();
// Convert the array representation of a positive decimal integer string back to the corresponding string representation (this is the inverse of `toArray`).
const fromArray = numberArray => numberArray.map(String)
.reverse()
.join('');
console.log(fromArray(toArray("9007199254740993")) === "9007199254740993"); // true
// Perform the increment operation on the array representation of the positive decimal integer.
const increment = numberArray => {
let carry = 1;
const incrementedNumberArray = [];
numberArray.forEach(i => {
let j;
if (carry === 0) {
j = i;
} else if (carry === 1) {
if (i === 9) {
j = 0;
} else {
j = i + 1;
carry = 0;
}
}
incrementedNumberArray.push(j);
});
if (carry === 1) {
incrementedNumberArray.push(1);
}
return incrementedNumberArray;
};
console.log(fromArray(increment(toArray("9007199254740993"))) === "9007199254740994"); // true
console.log(fromArray(increment(toArray("9999999999999999"))) === "10000000000000000"); // true
// Test if two strings represent positive integers where one is the other's successor.
const isSuccessor = (a, b) => {
const a_ = increment(toArray(a));
const b_ = increment(toArray(b));
return fromArray(a_) === b || fromArray(b_) === a;
};
console.log(isSuccessor("9007199254740993", "9007199254740994")); // true
console.log(isSuccessor("9007199254740994", "9007199254740993")); // true
console.log(isSuccessor("9999999999999999", "10000000000000000")); // true
console.log(isSuccessor("10000000000000000", "9999999999999999")); // true
console.log(isSuccessor("10000000000000000", "10000000000000002")); // falsenpm install big-integer
var bigInt = require("big-integer");
var largeNumber1 = bigInt("9007199254740993");
var largeNumber2 = bigInt("9007199254740994"); // any other number
var ans = largeNumber1.minus(largeNumber2);
if(ans == 1 || ans == -1){
console.log('consecutive ')
}else{
console.log('not consecutive ')
}