问题描述
#include <algorithm>#include <iostream>#include <cmath>#include <vector>using namespace std;int countPrimes(int n) { if (n <= 2)return 0; vector<int> arr(n, 0); for (int i = 2; i <= sqrt(n); ++i) {if (!arr[i]) for (int j = i * i; j <= n; j += i) {arr[j] = 1; } } cout << arr[2] << endl; int j = 0; for (int i = 2; i <= n; ++i) {if (!arr[i]){ arr[j++] = i;} } cout << 'j' << j << endl; int l = 0, r = j - 1; while (l <= r) {int m = (l + r) >> 1;cout << m << endl;cout << 'arr[m]' << arr[m] << 'n - 1' << n - 1 << endl;if (arr[m] == n - 1){ l = r = m; return l + 1;}else if (arr[m] < n - 1){ l = m + 1;}else r = m - 1;cout << 'l = ' << l << 'r= ' << r << endl;cout << 'm=' << m << endl; } cout << l << endl; return 0;}int main(){ cout << countPrimes(6) << endl; return 0;}
在程序中加断点，发现运行到return l + 1处时报错，报错信息如下
在VSCODE中还会弹出一个窗口，提示源 源未知 不可用
请问问题出在哪里了？谢谢了
问题解答
回答1：通常win平台非预期的sigtrap都是heap corruption。再看你的代码，第十六行arr[j] = 1; 明显有invalid write。所以vector<int> arr(n, 0);的n应该改大一点，比如n+1。
