C++分配1-9不重复随机数失败，求助排查代码逻辑问题

我尝试为变量A、B、C…I分配1至9的不重复数字，计划通过计数器方法实现：每次变量与其他变量不同则获得1个点数，累计8个点数时将该数字分配给变量。我编写了包含主文件、函数文件、头文件的三段代码（如下），最初使用<cstdlib>库时出现0、-1934、42130等异常数值，切换到<random>库后则完全没有输出。尝试取消使用std命名空间也未解决问题，怀疑代码逻辑存在缺陷，请问问题出在哪里？

主文件 #

#include <iostream>
#include <random>
#include "test.hpp"
using namespace std;


int main() {
 srand((unsigned)time(0));
 int A = 0, B = 0, C = 0, D = 0, E = 0, F = 0, G = 0, H = 0, I = 0, sum = 0;
 
 no (A);
 while (C == A or C == 0) {
    no (C);}
 while (B == A or B == 0 or B == C) {
    no (B);}
 while (D == A or D == 0 or D == C or D == B) {
    no (D);}
 while (E == A or E == 0 or E == C or E == B or E == D) {
    no (E);}
 while (F == A or F == 0 or F == C or F == B or F == D or F == E) {
    no (F);}
 while (I == A or I == 0 or I == C or I == B or I == D or I == E or I == F) {
    no (I);}
 while (G == A or G == 0 or G == C or G == B or G == D or G == E or G == F or G == I) {
    no (G);}
 while (H == A or H == 0 or H == C or H == B or H == D or H == E or H == F or H == I or H == G) {
    no (H);}
 
 
 
 cout << A << " is A \n";
 cout << B << " is B \n";
 cout << C << " is C \n";
 cout << D << " is D \n";
 cout << E << " is E \n";
 cout << F << " is F \n";
 cout << G << " is G \n";
 cout << H << " is H \n";
 cout << I << " is I \n";

   
}

函数文件 #

#include <iostream>
#include <random>
#include "test.hpp"




void no(int & x) {

x = (rand() % 9) + 1;

}

头文件（test.hpp） #

void no(int & x);

1. 随机数库依赖错误 #

你代码里用的rand()属于<cstdlib>库，和<random>库无关。切换到<random>后仍调用rand()，会触发未定义行为——要么编译失败，要么运行时无法生成有效随机数，导致循环一直无法退出，自然看不到输出。

另外，最初用<cstdlib>时出现异常数值，是因为没包含<ctime>库（srand((unsigned)time(0))需要这个库），导致time函数未定义，随机数种子无效，rand()生成的数值异常。

2. 循环逻辑冗余且存在顺序隐患 #

你逐个变量写循环判断重复，不仅代码冗余，还存在逻辑顺序问题：比如先处理C再处理B，B的判断条件包含C的值，虽然逻辑上能运行，但一旦某个变量的循环条件出现漏洞，就会陷入死循环。

3. 完全未实现计数器逻辑 #

你提到的“变量与其他变量不同得1分，累计8分分配数字”的逻辑，在代码里完全没有体现，实际用的是简单的重复判断循环，和最初设计偏离。

修复方案 #

方案一：修正随机数使用并简化赋值逻辑

如果继续用rand()，必须补全依赖库，同时用数组+已使用列表简化赋值：

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    srand((unsigned)time(0));
    int vars[9] = {0};
    vector<int> used;

    for(int i=0; i<9; i++){
        int num;
        do{
            num = rand()%9 +1;
        }while(find(used.begin(), used.end(), num) != used.end());
        vars[i] = num;
        used.push_back(num);
    }

    cout << vars[0] << " is A\n";
    cout << vars[1] << " is B\n";
    cout << vars[2] << " is C\n";
    cout << vars[3] << " is D\n";
    cout << vars[4] << " is E\n";
    cout << vars[5] << " is F\n";
    cout << vars[6] << " is G\n";
    cout << vars[7] << " is H\n";
    cout << vars[8] << " is I\n";

    return 0;
}

方案二：实现你最初的计数器逻辑

如果一定要用计数器方式，可通过比较已分配变量的数量来判断：

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

int assignNum(int used[], int count){
    int num;
    while(true){
        num = rand()%9 +1;
        int match = 0;
        for(int i=0; i<count; i++){
            if(num != used[i]) match++;
        }
        // 已分配count个变量，和所有变量都不同则match等于count
        if(match == count){
            break;
        }
    }
    return num;
}

int main() {
    srand((unsigned)time(0));
    int used[9];
    
    used[0] = assignNum(used, 0); // A
    used[1] = assignNum(used, 1); // B
    used[2] = assignNum(used, 2); // C
    used[3] = assignNum(used, 3); // D
    used[4] = assignNum(used, 4); // E
    used[5] = assignNum(used, 5); // F
    used[6] = assignNum(used, 6); // G
    used[7] = assignNum(used, 7); // H
    used[8] = assignNum(used, 8); // I

    cout << used[0] << " is A\n";
    cout << used[1] << " is B\n";
    cout << used[2] << " is C\n";
    cout << used[3] << " is D\n";
    cout << used[4] << " is E\n";
    cout << used[5] << " is F\n";
    cout << used[6] << " is G\n";
    cout << used[7] << " is H\n";
    cout << used[8] << " is I\n";

    return 0;
}

内容的提问来源于stack exchange，提问作者Devil's Advocate 2321